Ep. 3 The English Chemist: Cell site analysis, drugs, weird fingerprints, and egg fraud. With forensic science expert Dr. David Schudel (Full episode)

EP 3
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[00:00:00] Angela: Greetings all. And welcome to another episode of Secrets from the Crime Lab. I'm your host, Angela Swarts. Today we're going to continue on our conversation that we had in episode two with Tiffany Roy. And we're going to be speaking with Dr. David Schudel who works with an independent group of forensic experts. Dave, I'll let you introduce yourself to the audience. 

Hello everybody. My name's Dave Schudel. I've been a forensic scientist since 1991, starting with Keith Borer Consultants in the UK. But after that, I then worked in the, United States, creating the crime lab in Massachusetts. I was the government chemist for the Cayman islands for eight years. I went back to the UK to continue doing work as a consultant in forensic science. And then came back to Cayman and spent another three years as the scientific support manager for the Royal Cayman Islands Police. And now I'm back in the UK, again, just continuing the same role as I did before as a, essentially a defense expert, but ultimately it's just being a forensic scientist. 

[00:01:04] Angela: Primarily you're a chemist, but you've done quite a few different types of forensic analyses. 

[00:01:11] Dr. Schudel: I'm trained as a chemist, but you know, over the years I've accumulated several areas of expertise. A lot of it's chemistry related, including fire investigation, for example, but also I cross-trained into cell site analysis, which is a big area of forensic science in the UK.

[00:01:28] Angela: Tell us a little bit about what is cell site analysis, how does that... 

Well, cell site analysis... when every time you switch on your mobile phone, or in fact, in these days, people don't really ever switch them off. The phone is in constant connection with a cell tower and specifically an actual cell. Essentially for billing purposes, the companies that provide the services for the, telephone that you use so that the network that you're using, they will record if you make a call or if you send a text, they record which cell you use to start that. And for the, for a call they will also record which cell they use to finish it. And it's just for auditing purposes. So they can have an audit profile about what they're going to charge you for billing purposes, but the sideline of all of that is the positions of the cells that are providing the service and known that they sit on masts, but they also sit on the sides of, lights and football fields or on the sides of office buildings. Or you might see them inside tunnels and all sorts of places, but the positions of these masts, are listed in the documents. And so you can get an idea where the phone's been essentially from the list of masts that it's used at a particular date and time. 

So you can use it to, cooberate or dispute somebody's potential location at the time of crime was committed. Is that the general idea? 

[00:02:54] Dr. Schudel: Yes. that's the idea that it's, it is a very general area. So if you're trying to figure out whether someone was at home versus, I don't know, 400 yards down the street, it's probably not going to help you because...

[00:03:06] Angela: If they were supposed to be 50 miles away... 

[00:03:08] Dr. Schudel: Yeah. They say, I was in London and the crime was in York then if the phone was in York then clearly they weren't in London and you can also, it's particularly useful if you're looking at movement over distance. And one of the areas that's used quite a lot is someone who maybe is a drug dealer. They have a personal phone, but they also have a separate, drug phone or a burner phone if you like, or a drug line. And that's the phone that they do on the drug dealing work on. And they'll say, well, I don't know that I don't know that phone. That's not my phone. I've never seen it before, but you can use cell site analysis to show that, it's a bit of a coincidence that your personal phone goes on a trip all the way across the country for 300 miles and back. And this phone happens to go at the same time based on the cells that it's used along the way. And so you get very good cooberative evidence from that. And that's the basis of a lot of prosecutions into, you'd call it, drug dealing on county lines, drug dealing in the UK I don't know how the Americans do the same thing and the theory should be the same, but I don't know exactly how they do it over there. 

[00:04:15] Angela: Yeah, I'm not actually sure either. I have to confess that I had never even heard about it until you had mentioned, the work that you were doing with it. I'm sure that they do probably, do it. Cause, I don't know if it's the digital forensics people that do it. So if you're a digital forensic person, if you could reach out and email me and let me know, cause I'm curious,you can email at hello@secretsfromthecrimelab.com and let us know your thoughts about how the cell site analysis is used in the United States.

So the other thing, so the group that you work for, you're an independent group, but you do work on behalf of the prosecution and on behalf of the defense. Yes? 

[00:04:53] Dr. Schudel: Yes, that's right. 

[00:04:54] Angela: Do you ever find that there's a difference between the requests for analysis that you receive from the prosecution or the defense? Or are they about the same?

[00:05:04] Dr. Schudel: That's interesting question. I think at the heart of it, the requests are the same, not necessarily about what's driving the request and what we're asked to do, but as an independent expert, we know what we need. So we'll always go back regardless of whether it's prosecution or the defense, we'll go back and say, well, this is what I need. So we end up with the same information, whoever's instructing us. The only thing that can happen if you're doing work for the prosecution, is that further down the line, further statements and further, material might come forward from the defense and you might not get to see that at that point in time, but it could be relevant to what you need to look at.

So do you find that there's a lot of last minute conversations with the scientists that's maybe working for either the defense or the prosecution right before you guys go in, go into court and you're going to have a discussion. You're like, oh ... have an epiphany. 

[00:06:00] Dr. Schudel: Oh yes. the unfortunate thing is it's often the last minute and it can be avoided by everybody getting involved at an earlier stage, but it really depends on the case. So if I'm working for example, on the defense side and produce a report, most of the reports we produce are non-contentious. We it's a it's the belt and braces approach to forensics. We've looked at everything, including all the information that possibly the prosecution scientists didn't even see in the first place, looked at the whole context of the case. And we still agree with the findings and there's no duty to serve that report. So it'll just be noted and that'll be the end of it. As far as we're concerned, in some cases they'll be minor issues and they may or may not serve our report as a result. But they often won't trigger any real response either. And then there may be major issues, which is a, the minority of cases. But in those cases, they, they will trigger a response, but not necessarily involving the prosecution scientist. And so you still have the situation where the two of you end up at court and they look at you and go, why are you here? And you say, have you seen my report? And they go, no. And that's when suddenly everyone has to jump on board and they get to see the report and they can look at it then, but I ideally, and it is becoming more common that will happen before court. And you'll try and resolve the issues outside of court and weeks before trial, hopefully. And the idea at that point is you come up with a giant schedule of points of agreement and points of disagreement. And in that conversation, you can often resolve all the issues. Because what is often missing is the prosecution scientist hasn't been given the rest of the material that adds the context they needed to then reassess the evidence in that light and go, ah, okay. I see. I get it. Yeah. That's an alternate explanation of yep. I agree. this is a possibility. So in that joint approach, you can actually end up with just one joint agreement. If there's no points of disagreement. It's just a scheduled agreement. And then that can go to the court and without the need for either expert having to give evidence. 

So does sometimes one of the experts end up going anyways, just to explain it to the court. It's just, there's nothing to dispute it.

Yes, absolutely. If, but if it's agreed documents, then it will be up to really the barristers involved, whether they feel the need to have someone standing there. Or if they'll just read out the scheduled agreement. So it can go either way. If they want somebody there, then what can happen is they'll ask the defense expert to go as well. Just in case the prosecution expert just goes off the rails while on the witness stand. And then the defense expert can temper that if need be again, that's rare, particularly if you've already got a schedule of points of agreement, because it's more like a script at that point and they can stick to the main issues. But the question may crop up that was unexpected. There might be an answer that the defendant might, the defence team might not like, and they'll want the expert to review it and go into more detail. So they may ask you to be there. One of the things about, the trials in England and Wales is that as an expert, I can sit in the court well, technically through the whole trial, and by sitting in the car to quite often sit right behind the legal team. And so while the prosecution's expert is giving evidence, you're listening and then you can flag anything with the, with your defence team that might need a follow-up. And so you actually sit in the court and then the prosecution expert will sit in the court while you'll give evidence. And they have the same, role. And the reason is because ultimately as experts, we're not working for the defense or the prosecution we're working for the court. 

[00:09:39] Angela: Exactly. 

[00:09:39] Dr. Schudel: And so that's the role we take. And it's taken quite literally, you're an expert for the court, which is why you can be, having these discussions between each other, because the court considers as independent experts, both of you, you should have a discussion as experts and then come to some sort of form of agreement and disagreement and be able to map it out as professionals, which then assist the court and what they need to know. It doesn't matter which side you're on. 

[00:10:04] Angela: Yeah. In my previous episode with Tiffany Roy, she had... her experiences in the U S system is that there's not a very collegial atmosphere when it comes to prosecution scientists and the defense scientists being able to have these discussions and enter in a joint report basically to the court, it's very adversarial and she sometimes has difficulty obtaining all of the information that she would need in order to make an assessment of whether or not she agrees with the scientists that did the initial testing in it. Do you find that you have the same thing or is it pretty much if you ask for something, you have no difficulties having all of the relevant information disclosed? 

The idea of the role of the expert being for the court has been driven by the courts. So they're the, really the people who have demanded that the experts take a neutral stance and they will often request the experts get together. The judge might direct that the experts get together to discuss. And at that point, there's usually no problem getting hold of any information, particularly if the judge has ordered it. While you're trying to do a report, then the issues of disclosure often come up and you can struggle for a while to get information that you need to do your report. And I don't think it's done on purpose. I think there's just a lot going on and there's been a lot of austerity measures over the years. So there's a lack of people in the system. There's a huge amount of casework to get through. And so when you're asking for things, there's a temptation, I think for the, to think that disclosure has been met that, oh yes, we've disclosed everything that you need. No, you disclose everything that the case needs, to, as a bundle for the trial. But as an expert, I need to see raw data for example. I can't just use someone's report. I've got to know what the data is behind the report. I might... 

[00:12:00] Angela: Maybe at least a printout of the data... 

[00:12:03] Dr. Schudel: Yeah. And someone's notes. it, and in cell site cases. You might have, records running into hundreds of pages on an Excel spreadsheet. It doesn't benefit the court for them to see that, but I also can't use it in a PDF format. It has to come in as... in a format that can be used digitally, which then you can use with the software that we use to, to, review the data and getting hold of that can be quite painful because it's in a part of the police's systems that they're not normally using for disclosure purposes. So it's usually about getting hold of the right person. And normally we get it in the end. It just can take a while. Rarely we have to go to court and the barrister has to argue with the judge, say, we need this information and it's not being provided. Then the judge usually make an order that it will be done and when that happens again, it'll appear relatively. and in some cases, the information is very sensitive. If you're working on cases involving, things like terrorism or, sexual assault cases, where there might be indecent images of children is another good example. The information may be very sensitive. And so you, I completely understand why disclosure has to be managed very carefully. And what we can do is undertake memorandums and understanding, between us and the police, just to say, we'll only use the data for this. We won't disclose anything in the reports. It'll be kept secure. It will be destroyed at the end of it if need be. There's, a lot of mitigation could be put in place. you know, it's, I don't think anything, I don't think it's a game of sort of cat and mouse, if you like. I don't think anyone's deliberately trying to slow a process down. I think people are very careful about what they disclose. They're very careful about people's private data, not giving it to another party. So I think it's all been done in good faith. But it also adds a lot of time to the process, unfortunately. 

[00:13:45] Angela: So you've mentioned a few things that I want to, I wanted to touch on. First, I'm going to say for what you're talking about there, if we're talking about the ISO requirements, which I know the police aren't beholden to, but the forensic laboratories that are accredited would be, and that's the aspect of confidentiality. There's a whole standard just specifically about that. But a lot of times in the UK, the defense groups don't have the same type of accreditation that the forensic laboratory might have. And it does seem like the way the system works in the UK, it might actually not be conducive to the defense groups being able to become accredited as easily as a government laboratory would be. 

I think in terms of disclosure, the disclosure is managed through the, well through, ultimately through the crown prosecution service and the larger forensic providers or private laboratories that then are instructed by the police to have the work done the disclosures and because it disclosure managed at a different level, I think the lab's duty for disclosure, it's largely the same. And that doesn't matter whether we're accredited or not, they won't change that. I think the only thing that might make a difference in the future is whether being a defense expert, if you're not accredited, then that might be an issue for the court to consider, to say, well, you're not accredited, you shouldn't be an expert. But ultimately it's the court to consider whether you're an expert or not the crime of prosecution. So as an individual. Yeah. 

[00:15:17] Angela: Yeah. 

[00:15:19] Dr. Schudel: I think as long as the court considers you're an expert, then you have the rights to see the supporting data that the prosecutor's expert has used to form an opinion. And so that right will exist regardless. Because the often these cases it's pointless rerunning all of the material and re extracting the stains or retesting the samples because ultimately the, that, in a lot of cases, you can't do it again because it's a one shot deal.

[00:15:47] Angela: Right, it's been consumed. 

[00:15:48] Dr. Schudel: It's already been consumed. and also the work that's done is normally done to a very high standard. So unless there's a glaring issue and, occasionally that happens you know where there's,in a drug case, for example, where they've, ran the same vial twice, but given it a different exhibit number that, but that is normally what exactly. So when you look at the actual report, it looks like you've got two different that are both drug, say heroin samples. But when you actually look at the supporting data, you don't need to run them. You can run them again, and it will tell you the answer. But if you actually get the supporting data that underlies that report, you'll see on the analytical run that the vial was run twice by accident. And it will be obvious, but that's that's very, very where normally when you look at everything, everything's absolutely fine, but you need to check anyway just to see if there are any other issues involved. 

[00:16:36] Angela: So as long as all of the controls and the calibrations and everything is in order for that type of analysis, then you can look at the data and you can see, yes, I can agree with the data. There's not really... you're not questioning what they're, what they've done. So you don't really do a lot of retesting at all? Mostly it's just reviewing what the other laboratory did. 

[00:16:58] Dr. Schudel: Yes. A lot of it is a straight review. If there's a need for retesting, it's usually driven by something that's come out of the defense or perhaps in an account they've given or a story or something that's relevant to the case, but it hasn't been tested. So you might do a re-analysis to explore further investigation into the case where you wouldn't just reanalyze something for the sake of reanalyzing it. 

[00:17:23] Angela: So you wouldn't necessarily do the analysis. You might go back and say, I think, can you guys go back and retest to these other samples and just ask the lab that did the original analysis, especially if you don't have any issues with the work that they've done in the case, can you just ask them to do redo it or would you guys want to test that on your own?

Normal circumstances we normally choose our own laboratories and we test them ourselves. and that's just how it works. The lab might be contractually obliged to... Have, they've got a customer relationship with the police, for example? So they're independent scientists. We could ask them to do it, but that request would have to go essentially through the police to get it done. It has happened, yes. We've raised something as, as a concern and we've, requested that we reanalyze it and that concerns gone back to the officer in charge, for example, who's then said, we'll just get it done. And they've gone ahead and done their own analysis. 

[00:18:15] Angela: Do you find that most of the time when you're asking for additional analysis or if something needs to be reanalyzed, do you get any pushback or are they pretty generally pretty good about going? Okay. Yeah, we can do that. Well, the company's been around for over 40 years and one thing we've always maintained is to be professional and keep good working relationships with everybody. And so we don't go into a place to cause problems. We don't go to a place to cause problems or upset people. We go in there to work as colleagues, as professionals. And if you maintain a good working relationship, I think, ultimately if you put yourselves in the scientist's view that worked for the prosecution, if there is an issue you're going to want to know. And you'd like to know ahead of the trial.

I would.

[00:19:02] Dr. Schudel: You would not want to know on the witness stand and get a trial by ambush where you get bombarded with this thing at the last minute. And you go, are you just someone who just told me beforehand, we could have sorted this out. And so we've very much, tried operate with a lot of transparency and as a result,I don't think we get really much in the way of pushback. I think it's just part of how business is conducted. So there's an expectation, people are going to act in a certain way and that's how it goes. And, and then when it comes to having those discussions ahead of trial, that need to be had, you've got that basis for it and the mutual respect, or you can have a conversation without it, turning into a bunfight really.

[00:19:38] Angela: That brings me back to one of the things that you were mentioning earlier, that sometimes what you find is that you've been given more information in order to evaluate the laboratory findings in the larger context. And so a lot of times your findings or your report, when you issue one, it's seems like it's probably going to be a lot more complete than what the prosecution scientist maybe was able to do. And I know that some of the reasons why the prosecution scientists are not given all of the contexts, they're not given all of the information... they're only given a certain amount of it because there's this push to ensure that you're not biased in any way when you're doing the initial testing. And it does seem once you get to the end of the process, the prosecution scientists, a lot of times, or at least in my experience, it's almost like you're being criticized because your evaluation wasn't as complete as the defense, but you weren't given the same information. And in fact, nobody even asked you the same questions that were posed of the defense. So it does seem like it's a little unfair sometimes for the prosecution scientist, in, in, in some respects. 

Yeah. And that's exactly what happens. And bear in mind, the lab work may be done very early in the case as it's being investigated. And so what's been generated has been generated at that time.

[00:21:02] Angela: Yeah. It's an investigative it's at the investigative stage, not the evaluative stage.

[00:21:07] Dr. Schudel: Yes. And, but what might not happen is, for someone to go back to the scientists and say, we've got all this other information now, including the defence's statement, have a look at all of this and see if you want to reevaluate anything. I think that step often doesn't happen. I think they feel like they got the results from the initial forensic work that's done. They've got the rest of the case put together and then it just it's put in a package and it's,and there's nothing wrong with that. It's putting a package to really put to the defendant to say, this is what we've got. And I think that's appropriate because many times that might be enough for a defendant to say, yeah, okay, I'll put my hands up and say, yeah, I did it. And so you then negate the need for all the extra work to be done, because it's pointless. But if the defendant pleads not guilty, and then you'd like to think there was another step involved where the, there might be review process internally from the prosecution side. But in my experience, I don't think that really happens very often. 

[00:22:02] Angela: No, I wouldn't. I wouldn't think so. And then the workload, a lot of times, for the laboratories that are doing the initial analysis. It's so big. The idea that having time to go back and reevaluate a case is difficult. 

[00:22:16] Dr. Schudel: And so it, that's where the defense expert comes in and we will do the analysis and the evaluation. And,it may be that everything's fine. And the prosecution scientists will never hear anything more about it. Or the issues are found. And then, like I said, in the UK, there's a general push for it to be resolved. At least before the trial starts, it may actually be the morning of the trial, but at least there's an opportunity for everyone to get together and have that discussion. And then they'll get to see the rest of the information that they previously didn't have. But yes, the there's, there is a push to reduce context to stop the cognitive bias effects that you get from context bias, but the scientists... but the it's a bit of a paradox because ultimately the material that's sent to the lab in the first place, the exhibits that are sent to the lab in the first place are chosen by whoever's managing the case or their scientific support manager. So they're not gonna, if you take 45 exhibits from a bedroom, you're not going to send them all to the lab. Someone's going to say, let's, we'll just send this, maybe this bed sheet and...

[00:23:19] Angela: What? You mean, we can't test everything? 

[00:23:21] Dr. Schudel: Exactly. 

[00:23:22] Angela: We can't test those 200 exhibits that were collected? 

[00:23:25] Dr. Schudel: Because there's already a process in place where bias effects are in play and it's, before you can get to the lab.

[00:23:32] Angela: Yeah. 

[00:23:33] Dr. Schudel: And and there's nothing we can do about that because there's very, you can't send them into the lab. It's impossible. And, but someone has to make the decision and the people who make the decisions have to be ones who are familiar with the case 

[00:23:43] Angela: Right there... you have to have somebody that's going through and deciding based on the type of crime that was allegedly committed I need to send... these items are most likely to yield probative information. And then of course, when it does actually get to the lab, the scientist needs to know at least a little bit, so they know what they're looking for. 

[00:24:02] Dr. Schudel: Yes. you have to have an idea what , what substance am I looking for starters and then some idea of the events, but if you remove the context completely, it can, I mean, trace evidence is a good example. If you have a case that you sent the lab of a sexual assault case on the bed. Then the difference between looking for stains that have for DNA analysis versus looking for trace is a huge amount of work. And so it's useful to know upfront whether the suspect in the case is someone who had access to the room on a normal basis. 

[00:24:36] Angela: Yeah. That changes a lot. 

[00:24:37] Dr. Schudel: In which case... absolutely. Now, if you follow the,no, context information at all, you may be sending that the lab down Well, if you want to talk about scientists' morale, for example, that the scientist spends three days working on trace evidence only to find out that there's the suspect involved was routinely in this room.

And, yeah, you're gonna, you're gonna expect some kickback from that. 

[00:25:01] Angela: You mean I just spent three days taping these exhibits from... 

When in fact I could have been working on someone else's case. And the context is important and I think both sides need to know what context is important because the people submitting the analysis, the work for analysis might not necessarily know that actually it's highly important that the scientist knows that this is a person known to that location. 

[00:25:26] Angela: There needs to be some kind of a balance in there. Yes, we want to do things to reduce any kind of bias effects on the person doing the testing, but at the same time, if they need to have at least a little bit. 

And, I suppose at the end of the day, there's nothing stopping the scientist picking up the phone and saying, I need more information on this before I start the case, just to clarify some of these points.

[00:25:48] Angela: So I know in a lot of the large laboratories that perform biology and DNA testing, you end up having one person that is a senior level scientist that kind of does more of a case management aspect of it. And then they talk to the evidence screener and say, screen this evidence for these particular types of body fluids. Let me know if you see anything else. And then a different person's going to be doing the DNA analysis after that. And that case manager might be the person that's going through and choosing exactly what it is that is sent on to DNA analysis based on what the screener did. And I think that in some respects, that kind of, at least from the laboratory perspective might help to maybe they get more context from the investigators, but they pick and choose what they feed to the scientists that are doing the work at the bench. And what are your thoughts about that model? Is that eliminating the bias effects or is it still there, it's just at a different step?

[00:26:53] Dr. Schudel: I don't. I think that it can go either way with that, because you can end up the situation where the people at the bench are doing the routine analysis they've been instructed to do, but might miss something because they weren't aware of the need to look for a certain thing that someone further up might be aware of, but might not have appreciated that the bench assistant hadn't looked for it. And then it comes down to how well their review process are internally and whether they pick up on the things that might have been done or not done. So I, I think every time you add more people into the mix, there's a greater chance that you're going to end up at loose ends. And so one of the nice things about having one person doing the analysis from beginning to the end is you get a lot of continuity that the person will be very familiar with that exhibit. What was on it, what needs to be done and what needs to be reported. Every time you add another person, which you need to, because in big laboratories, you need that triaging approach. But anytime you have a triage, there's always that there's always a potential for a step to be missed out or not be communicated correctly.

Right. So you've, they've managed to improve efficiency of processing by that approach, but the quality of the case might end up suffering because no, there's no one person with ownership of it. Like you're saying that understanding of what did that exhibit look like? How did it present? What did I find? Was there something else I could go back and test if I didn't obtain any useful information from my original test? A good example is a drug case with four identical blocks. Each around visually, well, each were around 250 grams but visually you've got four identical looking blocks. When they were weighed they were reported as around 250 and one of them was around 150. 

[00:28:40] Angela: That's quite a bit different. 

[00:28:40] Dr. Schudel: That's quite a bit different. And when I looked at it, they were identical really. And so I weighed them all and they were all about the same weight. So the bench analyst had just weighed it wrongly. One thing that can happen is you don't quite get it on the balance right and the corner of it's sitting on the desk or something like that so it's holding a little bit of the weight. But whatever happened, they, they'd missed it, but they reporting scientist had also missed it. But had they gone and seen the box themselves, they would have seen that they all look the same. And so the fact one of them was underweighed would have just seemed unusual. And yet, because they are that one step removed, they don't have that same level of,scrutiny. And you don't have that same level of a second check. And so it gets reported, with one of them, I mean, it didn't help the defendant of course, because it's only got a hundred grams heavier, but that's how it goes. But I think that's the, that system, that's the weakness of that system. But the strength in that system is, that you can get through a lot more work because of the triaging system that's in place. 

[00:29:44] Angela: But that also points out why the role of the defense expert is so important. Like you said, most of the time you're agreeing with the results, but sometimes you find things. And if you weren't part of the overall process for, that, that scientific evaluation prior to a case going to trial, you could end up with a lot of miscarriages of justice. And it's not because somebody at the original lab or the initial lab was, a bad actor. It's just that sometimes things are missed. Even if you've got multiple people doing a technical or a peer review before issuing that test report, you need that external pair of eyes that's got a little bit of a different viewpoint and you can catch things like that. And if you didn't then, in this one case that you just use it an example, it would have been better if you hadn't found an error for the defendant. But a lot of times that's the defense eyeballs are needed to ensure that we're not having a miscarriage of justice. And again, not because people are acting inappropriately just because we're all human and we make mistakes. 

[00:30:52] Dr. Schudel: Yes. and there's two areas really. And I agree with you. I don't think anything has been done in malice in these cases. And in fact, the scientists involved are good at what they do and they're consistent and they're knowledgeable and they are competent. But there are two areas. One is the mistake. And so for the other example, I gave you where they run the vial twice by accident the machine and the quality checker missed that as well on the quality check that the same vial had been run twice, but with two separate exhibit numbers, that turns someone who was charged with, dealing heroin back into someone who was just using heroin.

[00:31:29] Angela: That's a big difference. 

[00:31:30] Dr. Schudel: It's a huge difference. And he was a known heroin user and he said, I have heroin. This is heroin. Now the heroin was a brown powder. The other one was an ounce of fine white powder. And it was glucose, I believe. So visually from the start, there was no question from my mind that visually these were two separate things. One, one looked like heroin, the other one didn't and somehow they got both reported as heroin. It was just, it was a mistake that had gotten through the system. And so having a separate check is absolutely essential, because until that was done, no one was going to go back and entertain the possibility this was a mistake. Because it was just assumed to be correct. And it's not because the people that did the work wouldn't have been happy to go back and do it again, because as soon as they find out about it, the first thing they did was essentially apologize and reissue a new report and, and acted absolutely in accordance in how an expert should react. It was just a genuine mistake. But then trying to get the focus back on fixing it really took a defense expert because we had to just reanalyze it and show, this is what it is. You need that sort of, that sort of level of push if you like, just to put the spotlight back on it. Now, the second one is the more common one and that's where the context is critically important, but it hasn't been explored in the context of that case. And when you start running through the context as a defense expert, and you come up with alternative propositions to what might've happened, that's, there's no fault on the prosecution expert. They've just reported their findings as they found them. But it's putting the it's really about joining the dots and putting the pieces of the case together in the wider picture and interpreting that and producing the report. And then that becomes something that there's no fault on behalf of anyone it's just about joined up thinking. 

So do you think that, is there a particular type of case that's more prone to those types of issues where you really need context to properly evaluate it? 

I'm not a biologist, so I can't really comment on that side of things. Although biology and DNA does have a very well set out methodology and ways to interpret the evidence, but that's something you can comment on.

it does depend, right? Sometimes sexual assault cases contexts does tend to be very important that you need to know if there's a consensual partner, you need to know if people are cohabitating. And there's a lot of context information that's helpful in those situations. 

But I think for me, fire investigation is an area that is very, very difficult and is massively context dependent. Because fires have the disadvantage that they destroy their own evidence as they go. And so when you're coming into a fire scene, you're already looking at a lot of the pieces of the puzzle have gone. And your having to reconstruct based on your own, essentially your education training, and experience where that fire has started and what might've caused it. The second step to that is that you can have a fire that's caused by a flame deliberately, and you can have a fire that's caused by a flame accidentally. And so there are huge opportunities for misinterpretation depending what other contextual information you've been given. And as a, as an expert, as a fire investigator, your opinion will be the same well it was a flame that I think a flame started this fire, but the bigger picture on that, how that flame got in contact with that fuel might solely be an issue for the jury. But as an expert, you're somewhat straddling that boundary between the findings of your examination and then what you think might have happened and what is possible. And then there may be information about the case you'll be totally unaware of that the police may have gathered which then will affect again. If, for example, someone says while I was in that area, but I had a cigarette and I left. And you as an expert go, I don't think that's possible for the timing of the fire, for example. But then somehow some CCTV footage comes out six months later that actually shows someone standing there smoking cigarettes, and you go, oh, I have to reevaluate this. It's influenced very heavily about external sources information that are coming in, and that could be from all sorts. It can be something even at the alarm, the alarm monitoring box in, inside a warehouse, for example, the company that manages that will have logs about what alarms are going off and when, which once you've received those might change your interpretation of how fire spread. But at the scene you might not have picked up. you might get information from people's handheld phones who took early videos of the fire, and you may have thought the fire start in a certain area, but then there's an early video is produced and it seems to be coming from somewhere else. It's so influenced by external information that could be fed in almost any time. And you are required to go back and reanalyze your whole approach to that fire. But I think because of that and because of the difficulties in piecing fires together, I think that's an area, like I said, that's quite prone to, cognitive bias affects, interpretation issues. And then really about context bias, the change in context then changes how you're going to interpret the scene.

So, But you always still, is it, I'm listening to you talk and I have all these parallels going through my head for when I'm doing a bloodstain pattern analysis. Like I go and I look at all the bloodstains, I identify how they were likely created, one type of activity versus another one. And then I'll go and I do need the contextual information to try to reconstruct the likely order of events and things like that. But I can never actually say, it's not, you never say this person stabbed this person. You just, you're only able to say as much as this person was likely in close proximity to this person, when this breach of their circulatory system occurred and then leaves it for the court to decide the rest of it.

and I, it really does depend on... there's a lot of things that come in after you've done your initial interpretation of the stains. And you always put this disclaimer, on your reports that if the information that I've been provided changes, the interpretation of the findings may also change and it seems like that's the same type of thing with the fire analysis.

[00:38:08] Dr. Schudel: And they're def-, they are very difficult cases. And the bigger the fire, actually now saying that sometimes even the small fires who incredibly difficult because of the, there might be very little damage and like very obvious what's caused the fire, but then you add all the different stories and the issues go beyond as a fire investigator, what you would normally talk about, except for, someone's going to want you to talk about it's because you're the only experts. And so you end up in this odd situation where I there's a tendency to say,this is all I'm going to do. And this is as much as I can comment on. But then when someone say, yeah, but someone was there, said they were there 10 minutes earlier, what do you think about that? And then you ended up in the making opinions about whether it's possible if I could have started 10 minutes earlier, or whether it's possible could've started with a cigarette? Could it have started with a hand-rolled cigarette? Could it have started with a cannabis joint? And then the things roll on and on from there. But even in areas where we consider that are reasonably set in stone, like fingerprints, for example, context is absolutely invaluable. And we've seen several cases where even in cases where with fingerprints, for example, we've seen cases where the defendants adamant they've not been to a scene, but their fingerprints had been found there. And I think a classic case was one that was a burglary. And he said he hadn't been there in four years, but he had been there and it was painted 18 months before, so he's lying. And he's obviously been back in committed this burglary. And you also had a previous, for burglary, which is why his fingerprints were on the system. Yet, it's amazing how it was missed, but ultimately his fingerprint was on the bottom layer of paint and when they painted over it, they'd use quite a thin paint and it just formed a paint layer around all the creases of the fingerprint. And they managed to lift the fingerprint off the top layer, which had come through two layers of paint. So it was from four years earlier. I think another one was,again, someone part we've talked about cognitive bias when people have their fingerprints on file for something they've done, and then they pop up in a burglary case or whatever the case is, it does shine a very big spotlight on them as the suspect. And it's quite hard to shake people from that. And so we had a young man accused of burglary of a school. And his fingerprints were found inside the window where someone had broken in and stolen some computers and you think, that's pretty cut and dry. Except for the orientation of the print was a bit unusual and it was quite hard to explain how he'd get his hand in a particular position. But his account was, he just, he was never there, but we, when we looked at it, the orientation of the print was in an area where you just, you really couldn't grab onto, if you were climbing through a window, it just didn't make any sense, but they kept, but the school was insistent that the windows were clean. So therefore the, the assumption is this is quite a fresh print. But, the fingerprint analyst involved, fingerprinted higher up on the frame towards the ceiling and an area which you really couldn't reach and found some fingerprints up there. And it turns out that was one of his as well. You're talking out, out of reach from floor level in a window that wasn't broken. The fingerprints have been there since he helped manufacture the windows 10 years earlier. They'd been there the whole time, but this is the problem with the concept, it does have an anchoring effect when you're dealing with things that the fingerprints have to be fresh. They had to be related to the scene and he's fingerprints on file. So he's a non troublemaker, for example. Yet actually you add the full context in there and piece it altogether, even in an area that seems relatively cut and dried as fingerprints, there's a story there that you would not have even exposed had you as a defense expert, not got in and naturally just worked it through, work their way through the problem. And then asked the question. Did this person have anything to do with making windows ten years ago? It was ten years, we didn't know when, but it turns out it was when he was a teenager working in a factory and the factory confirmed that they did actually install those windows.

[00:42:11] Angela: That is interesting because when you're in your, especially if you're a large lab and you have a large caseload, it's just get the evidence, look at the evidence, did you get a good identity, run it through the fingerprint database. Oh, we've got to hit. Let's go. And then you pass that on to the police and the labs done with it. They wouldn't necessarily have known that print was lifted from this awkward place, way higher than a person would regularly be reaching up to touch. 

No, and I think that's really where defense experts come in. In most cases, there's no problems. We agree with all the findings. It's those cases where actually it's, you're the one in million chances that seem to crop up quite a lot when you're doing defense work. It's those cases where someone needs to check and it has to be an expert because no one else is going to spot this. And you need that expert check too. It's the belt and braces to make sure that those rare cases come along, where actually there is an alternative and perfectly innocent explanation is caught because in that case, as an example, that I've no doubt, really someone would have found them guilty the jury on the basis of the evidence they'd put together. And he would have gone to jail for a crime he didn't commit. But the defense expert managed to figure out what had actually happened. And it was a perfectly legitimate explanation. In fact, it was the only explanation. 

[00:43:38] Angela: And it's not because anybody from the law enforcement side or the PR or the laboratory side did anything wrong. It was just, they didn't put all the information together. 

[00:43:51] Dr. Schudel: Absolutely. And the police are not in the business of looking for innocent people. they need to be investigating and looking for crimes and finding criminals. I only, the only thing I think is when a defendant puts together a story, whether or not you think it's the truth, there's an opportunity to look at it again and go, that's the story given. We can investigate that, but then that's going to take a lot of time and effort it, or it might not be on the agenda for that, for the amount of work that they're being tasked with at any given time. And so it then falls to the defense expert to be asked to say, this is the account given, can you have a look at this? And so that's where we come in and we take a look at it. We see what we find 

[00:44:38] Angela: Now you've done work... like I said, your group doesn't just work for on the defense side of things. You do work on the prosecution side as well, sometimes 

[00:44:48] Dr. Schudel: Yes, we do family law in civil cases as well. 

[00:44:50] Angela: So have you ever had any cases where, you're working, at the investigative stages, the initial part as the, hired by the law enforcement agency to come in and look at a case and like what your findings are maybe disagreeing with, like a pathologist's findings or something. So you've got two sets of scientific findings and they're not agreeing. 

[00:45:13] Dr. Schudel: Yes. it, with a little care though, because sometimes the pathologist may have made a comment. For example, not might be outside of the direct medical. And so they may be discussing something that's not really related to the pathology itself, but just a more generic observation. And so we might come in and have a look at that and go, yeah, actually, no, we don't agree with that. I think when the police come to us, it's quite often cases that are quite unusual and they can't find their regular suppliers of forensic services to help, so we will get involved. And, because we were willing to have a look at it and, try and figure out a way of answering the question.

[00:45:54] Angela: You do some experimentation sometimes to try to reconstruct what may have happened? 

[00:45:59] Dr. Schudel: Oh yes. the, one of the nice things about... it's interesting, what requests we get. we get a request, for example, do you have a biomechanical reconstruction engineer? And you said, why? I said, we want to know how someone might have fallen out of a window. And I said, we'll just make a window. As long as you've got the measurements. And it's been fully, there's a good scene reconstruction done at, at, at the scene. And so we've got the measurements, we've got photographs. We can actually just build a window and reconstruct it and then see what feels natural and what doesn't. So if you've got some versions of events, you want to look at them, we can actually just essentially try and fall out of a window, obviously not from a height. 

[00:46:40] Angela: So did you do that personally? 

[00:46:41] Dr. Schudel: Yes. Yeah, we've built a, we built a window, we set up the bed and we got the measurements how they should be. And, you try different things. And the nice thing about that is you can model stuff in a variety of ways, very quickly using yourself as the person and try different ways to see what might happen, what might not happen. And it can rule out a lot of possibilities, quite quickly. And that might be extremely helpful to the case. Well, this is what didn't happen. And then you might just be left with a few possibilities for people to consider while it, yeah, there could be, I don't think there were next to the bed, they had to be on the bed for example. Which might have a huge bearing on the case. 

[00:47:22] Angela: Yeah. And when you're talking about windows, for those of us in the, North America, we're probably not familiar with the types of windows that are often seen in England, especially in old buildings. So you're not talking about, the standard American bedroom window. These are old Victorian homes a lot of times. So these are massive windows, walkout windows.... 

[00:47:42] Dr. Schudel: Yeah. So they could be, there could be large opening windows. but also we do have modern windows that open that have large opening windows inside them that can open fully without locks on them and for example, so you might have a sideways opening window and you can still fall out of that. Then the question might be with someone sitting on it or, could they trip and fall, could somebody run in jump, but then again, create the questions come out of what the specific case is. And some of these cases aren't necessarily criminal, sometimes people just want to know an answer and it might be, it could be a coroner's case, for example, or it might just be an investigation into something that's happened at a facility. So you just reviewing everything to see, this is what might've happened. This is what didn't happen. And it might help a company reassess how it might be doing things in the future, not the window case, obviously, but if there's been some kind of failure or someone has gotten hurt, they might want some idea of things to look at or even try to reconstruct what happened. Just so they understand what happened so they can then rectify it in the future. 

[00:48:44] Angela: So this case is more fun than some of the run of the mill cases because you get to go and experiment and fall out windows? 

[00:48:50] Dr. Schudel: Absolutely. one of the most interesting cases I did was egg fraud.

[00:48:54] Angela: Egg fraud? 

[00:48:55] Dr. Schudel: Egg fraud. This is, where you, I don't know what you call it in the US but we call them battery hens. But, the caged hens probably. So they mass produce the eggs are produced by hands and cages. And, 

[00:49:07] Angela: I don't buy those eggs. 

[00:49:08] Dr. Schudel: Well, exactly, but they are, they are mass produced that way. And then you have free range eggs, which are kept in very different conditions, but they're far more expensive to make. And so free range eggs tend to be a lot more expensive than the battery ones. Now, if you have a box that says free range and you put in battery, or caged hen eggs in it, you can imagine you have a sizeable markup. And essentially it's fraud. And the one case it's a, someone calls up and says, my client's been charged with egg fraud and doing precisely that They have caged hens but they've been charged with marking up boxes as a free range and, putting caged eggs in it and making all this money. And, it's a difficult conversation to have at that point because there is no egg fraud or egg expert, if you like. The people who do the analysis, that's what they do. And none of them's retired and become an independent expert in this area. It's a relatively new technique anyway, but it's done with ultraviolet. And I'm a chemist. I understand ultraviolet very well. I understand how it's used and I understand the principles, but ultimately you have to tell the client, I don't know anything about this. But, his solicitor was quite open and said, if you don't do anything, I can't find anyone else who's going to help me. And we might as well just put our hands up. But he's absolutely adamant he didn't, he hasn't done anything. And so I ended up in a darkened room with two egg experts who do this day in day out having to, and they know, I've know, they know I don't do this, and I've never done this before. And you've got that situation where, how do you introduce yourself into that situation? and still managed to keep standing. And I just looked at him and said, why don't we pretend for a moment? I don't know anything about what you do. What would you, how would you explain it to me? And they both looked at me and one of them said, let's go buy some eggs. And we went and bought eggs, free range. We went and bought eggs for the battery and the caged hens. And you got out the UV light and he had showed us exactly what it was. And it's all to do with the way the marks sit on the eggs when they're first laid. And when they first laid, whatever they contact, they pick up that surface. And you will either see cage marks, which are like tramlines, or you might see stippling, which could be AstroTurf, which is free range or straw. You might see starw marks, which are like criss cross marks and a random pattern. 

[00:51:31] Angela: And so it's almost like using a UV light to look at bruising on a victim or something. You're just using it to look at the egg. 

[00:51:37] Dr. Schudel: Yeah. And it very straightforward. it's, those are the cases that are actually fascinating when you get into them and they're challenging as well. And a lot of them are very niche and there is no real expert to do any of these sorts of cases because they're niche and they're challenging, but then you just have to go back to applying scientific principles . 

[00:51:57] Angela: I think the egg fraud case kinda was a nice cap on the episode. If anybody's interested in contacting you, maybe they have a very odd case that they've been looking for an expert for a long time. can people reach out to you 

[00:52:12] Dr. Schudel: Yes, of course, 

[00:52:13] Angela: ...and ask for help? Okay. So I will make sure that in the show notes, I link your details. So if anybody's needs to get in touch with you that they can. 

The other thing I wanted to see if I could ask the audiences to remember that this podcast is for educational purposes and so we would definitely appreciate your support for the podcast. There's also going to be a link in the show notes. So if you're interested in supporting the podcast so we can keep bringing people onto the show and having these interesting conversations. I'm pretty sure most of the audience didn't know that egg fraud was a thing before today. And , the latent prints examiners are now all going to be rethinking all of their cases for any prints lifted off of window sills after this discussion, so did you have any closing remarks for everybody? 

[00:53:02] Dr. Schudel: Oh, I think the in closing, I think if you're someone who is working on cases, whether it's for the prosecution defense, whether you're working as an advocate, or, a representative or legal representative, I just think it's the value of defense expert just can't be understated. In many cases, it'll lead you to where you started at, and that it will be the prosecution scientific work could be absolutely fine. I think that, but there are just a certain percentage of cases where there are issues need to be resolved and you won't necessarily spot them unless you have an expert involved and it's something to, always bear in mind, I think.

[00:53:40] Angela: Yeah. Yeah, absolutely agree. Thank you for taking the time to carve out some of your vacation to come and talk to me. I really do appreciate it. And again, to the audience, if you have any ideas, for additional talks that you'd like to hear or ideas for episodes, or if there's anything that you would like to comment on, or if you had some interesting cases or some unique experiences that you would like to share, I'm going to start collecting some of that information. We might do an episode in the future from the mailbag, so to speak. So if you could email that to hello@secretsfromthecrimelab.com, I would appreciate it. And thank you guys again for taking the time to listen.