A listener production.
Welcome to Crime Insider's forensics. For those joining us for the first time. My name's Catherine Fox. I'm a former GP, crime author and screenwriter. I'm enthralled by forensics and have spent thousands of hours researching for books and screenplays. So I thought, why not turn my research into a podcast? Every week you'll be joining me in discovering how forensic science is helping solve high profile crimes in Australia and
around the world. This week, the fingerprint science behind one of the world's most contentious homicide investigations.
It was just that one fingerprint and how it was used in this particular case that created enough doubt in the jury's mind that the only outcome that they could proceed with was an acquittal.
Doctor Scott Chadwick is an expert in finger mark detection at the UTS centre for Forensic Science. His research focuses on pushing the boundaries of fingerprint analysis, from improving conventional fingerprint detection methods to producing prints on challenging surfaces.
We're actually able to recover fingerprints from documents for up to 70 years.
Our conversation begins with the officially closed but unsolved Engelbart's murder investigation. It's a story where a single fingerprint affected the outcome and determined whether the suspected killer was acquitted or convicted. Ingle Lotz was a 22 year old master's student. She was studying mathematics in University town of Stellenbosch in South Africa. She was found in her very secure apartment block, sitting on her lounge cross-legged with a magazine in front
of her in a very relaxed position. But the tragedy of this is that she was bludgeoned and stabbed multiple times in what seems like a very violent, very targeted attack. And police automatically looked, as they usually do, to the people who were closest to her. And as it transpires, her boyfriend, Fred VanDerveer, had a fight with her that morning. She'd written a note to him and told someone she'd met at lunch that their relationship was over, so police
automatically targeted him as the most likely suspect. But can you please talk about why that was not the wisest move for the police to make at the time?
Yeah. So a key part of this particular case was that they recovered a fingerprint on a DVD case. So the events leading up to her murder in the morning, she went to university. And as you said, she had her lunch with a friend. And then on her way home, she went to a video store and picked up a DVD to watch that evening. And when she came home where she was living, it was a secure compound. There wasn't any signs of forced entry. You needed a.
Remote control to enter and exit the compound. Yes.
It wasn't CCTV cameras at that particular time. It was in the early 2000. But whoever committed the crime, it's believed that Inga knew that person.
So they had access to this community?
Yes. Or Inga recognized that person and then let them into her house.
We should probably say, too, that she was wearing pajamas, and she was apparently a devoted Christian and very modest, and her boyfriend was even more conservative and didn't approve of her wearing, um, thin straps. And unless he was with her. So to be in a position where she
was wearing very casual pajamas. Given the context that she and her partner also allegedly had no physical contact because he believed that any physical contact could lead to sexual activity in a relationship, she therefore, in that context, it wasn't just like anybody sitting there in their pajamas. For her, this was an intimate situation. So I think that's easier to assume that someone who was in her apartment was let in. And to be in that casual position, sitting,
reading a magazine. She obviously didn't suspect anything.
Yeah, absolutely. She was obviously very comfortable in the person that she invited in. If you're in your pajamas, you're in a state of relative undress, but you would be comfortable with the person. Otherwise you put a jacket on or you'd want to cover yourself and the other side to interpret it is that perhaps she wasn't expecting a visitor that evening, in that she was in her pajamas to watch a movie at home and then go to bed and not expecting someone to come over.
From what I've read at the scene, there were seven police plodding through the crime scene, and they weren't necessarily experienced, but obviously they had to try and find evidence, and fingerprints were one of the first things they started with. So can you talk about the fingerprints that were taken, how they were identified and where they were taken from?
The fingerprints that were taken, or a key fingerprint that was recovered from the crime scene, according to police, was that there was a fingerprint that was linked to Fred, her then boyfriend found on the DVD case. So it's important when we think about this type of evidence, is that we can't specifically date when a fingerprint is deposited. We don't have that technology to be able to do that.
So sometimes we need to use additional information around the context of the case to help us recreate events or understand what happened during the events of a crime. And so, because he had been there earlier that day, recovering a fingerprint at the house could be explained away, is that it was deposited before the crime. Uh, it was just their usual, you know, activities that they were doing together.
You expect to find them on the bathroom door or a sink, maybe?
Yeah. Just. I mean, we touch a whole bunch of things when we enter rooms. If we see that tables, we do it completely unconsciously. So the key part here was that because she had gone to the video store that afternoon and rented that specific DVD, recovering a fingerprint that matched Fred on the DVD case, put him in that apartment in that afternoon, and it was indicating that he was there after the initial fight and disagreement in the morning, and then also her day at university at lunchtime.
And he'd been denying being in the house since then.
Yes, absolutely. So it was, uh, was putting him in her apartment that afternoon and it went against what his story was.
So when the fingerprint is go in, what is their process to take fingerprints and what do they target.
With any sort of examination? The first thing that we would always do is do an optical examination. So we will do a light search. So using very basic colored torches, the crime scene investigators will do a search. Now the areas that they're going to focus on usually are around points of entry or places where it's likely that there's
been contact with someone's hand. So door frames not so much door handles just because they tend to be curved and really tightly curved surfaces are hard for us to image and.
Recover even though they're metal.
Yeah, even though they're metal. Whereas if you open a door, you'll often push the handle down and then use your other hand to to push the door open. So usually around shoulder height is where they'll they'll focus specifically around window frames, particularly at the base of the frame. If somebody is climbing through a window, they'll put their hands on the frame and then lift themselves up to get inside or to exit. And it's usually just those places
where it's suspected of high touch. But then where the likelihood of recovering a usable fingerprint is going to be high. And. Focusing also on items of interest when they do their initial examination. There is if we go and try to develop everything, we're going to create a big mess, but we're also going to create, if there are fingerprints that
we recover, is it going to be useful? So there is a bit of hypothesis formation that the crime scene examiners will do, and asking questions of where looking at the scene, looking at the the type of crime that occurred, where is the most likely place to recover a usable fingerprint.
So what are you actually using to recover the fingerprints?
So at a crime scene, the most common development method that we will use is powdering. And powdering is where we would use a very fine powder. In a lot of cases we have black fingerprint powder, which is a form of activated charcoal which is really useful for surfaces like metal, like glass, anything that's light in color.
Because you get a contrast.
Yeah, you can image it. You have your your white light and you can image it with your digital cameras very, very easily. If the surface is dark or it's reflective, if it's got background, we might use other more specialized powders. Um, they might just be a white powder. So one we use is titanium dioxide. Or we will use what we
call fluorescent or luminescent powders. And this is where using the colored lights and special filters on the camera, we'll be able to remove any interference from the surface to enhance the contrast.
So you remove reflection and other confounding variables.
Yeah. So if something is very highly patterned or textured, if you have a regular black or white powder, the background that that finger mark was deposited on can sometimes interfere. And the goal here is to try and get the highest quality finger mark so that we have the best chances of making an identification. And so by using fluorescent or luminescent powders, we can reduce the interference from the background and then produce a mark of hopefully identifiable quality.
Do any of those techniques ruin the items?
The ones that we use at the crime scene can be cleaned very easily. There are usually just wiped down with some disinfectant and spray and wipe. But if we're collecting samples to then analyze at the laboratory. So certain types of evidence we can't develop with powders. So we would have to collect it and take it to the laboratory.
And in a lot of the cases for the laboratory development methods, they're damaged beyond repair or they're exposed to chemicals which are hazardous, that we wouldn't feel comfortable returning back to individuals because it may not be safe for them to to use them.
So in this scene, I mean, the first thought I had for a DVD case is they're generally generic. This was a generic DVD case, so the person at the store just grabs the next one that's empty. So it's not specific. So you can't then go back. Who who borrowed that DVD before you, and how many fingerprints on earth would be on a DVD case that had been hired out repeatedly, and chances are not wiped down very frequently?
I just thought it was interesting that they targeted a DVD case, and they may not have known necessarily when that was rented.
Yeah, it definitely raised some questions, but it helped the story that the police were wanting to.
Fit it.
Exactly because it put Fred in that location in that afternoon where he didn't have an alibi or his story didn't match up. So it was very much a gotcha type piece. It was what they would call a smoking gun, I guess, because it it put him in that apartment that afternoon and it could not be explained. He'd already given his story and said he wasn't there, but this was seen as well. According to the evidence that we've recovered, you were there. You're lying. That implies some level of guilt.
So you'd like DNA. People assume that that's, um, incontrovertible that that that is the absolute gotcha moment. So why was that challenged in this case?
Yeah. So there was a few interesting things with this particular fingerprint. So the first one was that the evidence that the police submitted, there was no recorded image of the fingerprint on the DVD case. So when we would go to a crime scene, if we develop a fingerprint at the crime scene, we will always take an image of that fingerprint, because that is a direct indication that we have recovered and developed that fingerprint on that particular surface.
It's shareable, it's reproducible.
It's it's trackable. It's it's will have an individual number. And we can then add that into any sort of crime scene reconstructions that we do. It helps us understand what happened.
And you have a fixed chain of evidence.
Exactly. We have a chain of custody and the image is recorded. It's linked to that particular evidence item. Timed times. Yep. Time stamped everything. So it's trackable. Essentially, once we image that fingerprint at the scene, what would happen is in some cases they might take a lift. So using either a gelatin lift or a special type of of tape adhesive, they.
It will take that powdered finger mark or fingerprint and lift it off the surface to then take back to the laboratory if they wanted to do any further imaging or analysis in case there was, you know, an issue at the crime scene with the photography. So in this particular case, there was no recorded image of the developed fingerprint at the crime scene. There was only an image of the tape lift. And that in itself introduced some doubt into that piece of evidence.
Questioning from what? Was that actual fingerprint lifted? Yeah.
So the police were reporting that it was recovered from the DVD case, but without an actual image of that develop marked on the DVD case, it could have come from anywhere.
Is there a way of differentiating whether this was taken from a DVD case versus another item in the apartment?
Yeah. So in this particular case, because of that initial doubt, Fred's defense team reached out to a range of international fingerprint experts because there were some interesting artifacts that couldn't be clearly explained by police on the on the lift. In those particular cases, the lifted print had a thin white line at the top and a smudging that occurred
on that same line. The other point that was curious, but could potentially be explained, was the fingerprint orientation was slightly curved, and there were just some questions about how this could have happened or how this could have been recovered from a DVD case. So the fingerprint experts went about and conducted a series of experiments using a range of DVD cases, different types of plastics, different types of shapes.
Which are flat DVD cases.
Which which are flat, and then try different orientations of how they held the DVD case, the positions that they held it in.
Yeah.
And did an experiment and did a scientific experiment to try and reproduce those three factors. The thin white line, the smudge that occurred on the white line and the curvature of the finger. And throughout all of their experiments, they were not able to reproduce those three artifacts in a repeatable and consistent manner in any of the circumstances
that they conducted the experiment. And it wasn't until they trialed other types of surfaces that they were able to reproduce some of those characteristics, and the one where they were able to successfully reproduce those characteristics was by lifting a fingerprint off a glass.
A rounded glass, a.
Drinking glass, yes.
So why is a fingerprint on a rounded glass so very different?
Well, it's to do with the characteristics of the surface that we deposit the fingerprint on. So as you mentioned earlier, a DVD case is a very flat and smooth surface. There is the, the edges of the of the case, but then the edges are also quite rounded and they're not a thin sort of edge. It's more yeah, just a bit more of a curved edge. Whereas the drinking glasses that we have, well, they're quite curved in their nature. And the lip of the glass is also quite thin.
So the structure of these items are very, very different. And how we handle them, how we use them will leave different types of impressions when we touch them.
And from different parts of the fingers as well.
Yeah, if we think about how we hold certain items. So if we're holding a DVD case, we might put our thumb on the front and have our four fingers at the back and our fingers will be quite straight along the straight edge. Whereas if we think about how we hold a glass again, we might have that same position where our thumb is at the front, but the curvature of our fingers as it wraps around the glass is going to be different. The parts of our finger that are in contact with the glass will also be
slightly different. Our fingers tend to curve slightly upwards when we have curved surfaces, particularly the the index finger compared to the other fingers that we have and. If we take it off, we'll see more of the towards the palm.
Because that's what we we don't normally trust for the drinking vessel. If it's glass. We normally take the weight in our palm. Yeah. Rather than rely on a couple of fingers to hold it.
Yeah, exactly. So when they did this experiment, they lift, they powdered the fingerprint off the glass. Uh, they then lifted it. And what they found was the thin white line at the top was actually the lip of the glass, because there would be some powder developing, just sort of sticking to the edge. Usually when we drink, there's some moisture there. And powder fingerprint powders are adhering to moisture. It's not a chemical reaction that's occurring specifically with the fingerprint.
It's just sticking to the sweat and oils or just any moisture that it can get into contact with. So there was some thin powder being developed on the lip of the glass. And then that that smudge that was occurring across the thin white line was actually a lip print that had been developed because as you drink a glass, you take your lip to the edge and you're leaving behind, not as identifiable as a fingerprint, but still able to be developed with with powder.
So if that was found in the apartment and the police allegedly took it from a glass, not from the DVD case, then that blows a massive hole in their prosecutors and story. In terms of glasses in houses, does a dishwasher remove every fingerprint? Does rinsing remove fingerprints? What is likely to be still there after things have been washed.
In fingerprint science? There's there's two sort of divisions. There's what we call non-porous surfaces. So these are things like metal, glass, uh, ceramic tiles where when we touch that surface, the sweats and oils from our fingerprints will just sit on the surface and it won't seep into that surface, so they're not well protected. So if we wash that glass or that item, we would not be able to recover a fingerprint afterwards because the sweats and oils have been washed away completely.
Unless that person puts it in the draining tray or puts it in the cupboard again. So then you've got contact again.
Yeah, since the last contact. And then the other area of fingerprints is looking at the other area of surfaces is the porous. And this is things like paper and cardboard. Now in these particular surfaces the sweats and oils will seep into the surface and get trapped in the paper or cardboard fibers. And in those instances they're protected. So we're actually able to recover fingerprints from documents for up
to 70 years using specialized chemical detection techniques. So in those instances, if you wash it in water, if you throw it in a sink and try and wash it up and then dry it later, some of the components of the fingerprint will be washed away, but some components will still remain, and we can choose different development techniques to target specific components.
This was a big, big trial with lots of international experts involved, which is unusual.
Absolutely.
So what happened when these international experts reproduced and challenged whether or not that fingerprint was on the DVD?
Yeah. So it created enough doubt in the case for a mistrial to proceed because. The police were not able to produce that image of the fingerprint being recovered or the fingerprint being developed on the DVD case. And so when the police were asked to provide this piece of evidence and they were not able to that particular evidence, the fingerprints was stricken from the the proceedings and could
not be considered in the judgment. And without that timing of the fingerprint being on the DVD case in that particular afternoon, other elements became a little bit more circumstantial. It could be explained away. And so it created enough doubt in the minds of the judge and the jury that it was not able to move to a conviction.
We should probably mention what happened to the DVD case. Why was that not held in evidence?
So there's two minds here in that the DVD case in question either wasn't initially powdered and there wasn't any finger mark recovered on there, or it was powdered and followed the particular proceedings, but there was no usable or identifiable fingerprints developed. And that couldn't specifically link to Fred because, as you've mentioned, if you pick up a DVD from a video store, it's very unlikely to have been cleaned earlier. So there may be a lot of background fingerprints on there.
So there may have been evidence that he touched it, but it wasn't enough. There wasn't enough identifiable information to confirm that it was Fred's. So this was seen as a way to assure an outcome by having an identifiable fingerprint that they said came from the DVD case, which would then corroborate the story that the prosecution were wanting to put forward.
One of the things that I found incomprehensible in this case was that apparently the police handed back the DVD case to the DVD shop.
Yeah. We talked earlier about evidence integrity and chain of custody. Yes. And that's obviously an example of what not to do. And in particular, it's probably because just to speculate that they didn't think it was important or it didn't have value at that particular point in time.
Presumably if they had dusted it, they would have had to have cleaned it before returning it to the DVD store. Yeah. So the whole story really does fall apart, doesn't it? In terms of credibility and plausibility on the part of the police's behaviour?
Yeah, absolutely. It really put a spotlight on the police conducting that investigation and for good reason, because fingerprints are an important piece of evidence in a lot of criminal investigations, and they carry a significant amount of weight because they can be used to identify an individual when we use it appropriately and for the purposes that they are intended. They are an incredible, useful tool. But they can be manipulated or used inappropriately to achieve a particular outcome that
benefits a party. And when we use science in that way, or use evidence like fingerprints or DNA, it's where we get cases like this and it brings the entire forensic discipline into disrepute and dis, you know, disregard. So it just really highlights the value that forensic science is an important tool in criminal investigation, but it always comes down to who wields it and what their intentions are. And as a forensic scientist, you need to be unbiased in
what you do. And while in some cases you assist police in investigations, you're not there to achieve a particular outcome or get a specific conviction. That's not not our role.
It seems to me it's a lot in some way. There are parallels with the OJ Simpson case in that part of the evidence found, as I understand it in OJ's trial, was that someone had deposited a bit of blood, but it actually had the preservative from a blood tube taken, and to have done that is beyond my comprehension. But it then absolutely tainted all of the evidence, because if one bit of evidence was fraudulently placed, what else was rigged and and incorrect and inaccurate and what else was
a fed up? So you can see why a jury would suddenly doubt the science.
Yeah, absolutely. And I think the parallel to the OJ Simpson case is is accurate. It's important. And it raises another point in that the crime scene is an important part of the investigations that we do. And. It's not something that we can go back to and retrial or re if we make a mistake at the crime scene, that mistake carries all the way through the investigation, and we will only get one shot to do things appropriately.
And by, uh, you know, by the standards that we have and in the OJ Simpson case as well, there was quite a lot of issues around the crime scene investigation and how that was investigated. And once you make those mistakes, the genie's out of the bottle. You can't put it back in. And it's the same in the Engelhardt case where. That initial crime scene was questionable in
that investigation. And while it may be that Fred was guilty of that particular crime because they didn't follow the right procedures, didn't do as they should have, they wanted a particular outcome or a focused decision. They've messed up their chance to now go back and give justice.
He was acquitted. So he can never be tried again.
Yes, absolutely. And to this day, it's still it's an unsolved case. And there's no.
But it's closed. Yeah, it's a closed case, but it's unsolved. I find that really sad for the family. And apparently the family did try to sue Fred VanDerveer in civil court, but it just became too traumatic for the parents.
Yeah, it's absolutely heartbreaking that all of the other evidence that you've mentioned indicate that it was Fred. There's no other suspects in this particular case, but it was just that one fingerprint and how it was used in this particular case that created enough doubt in the judge and jury's mind that the only outcome that they could proceed with through the legal system was an acquittal, because of the misuse of that particular piece of evidence.
And the defense's job is really to just raise reasonable doubt, but the prosecutor has to prove beyond reasonable doubt. So if you muck up any of the forensic science, you've left this gaping hole in the entire case, and intelligent defense and objective scientists hopefully will be able to raise those questions that should have been asked initially.
Yeah, absolutely. And I think that's the importance of science in in the courtroom and being objective, because if we flip it in an instance where an individual may have been innocent and that particular item is misused and we don't cast a reasonable doubt, that item remains, then we have instances where people are imprisoned unjustly. Exactly.
In terms of other ways of getting fingerprints in a crime scene like that. Having lots. Could there have been any fingerprints on her? On her body, on her throat. Neck where she was assaulted?
Um, so it is possible the challenge for us, from a forensic science perspective, is there is no reliable method for us to recover fingerprints on the surface of other people's skin. And the reason is, is that the components that we target, whether it's just general moisture with powdering or whether it's the sweats and oils from our skin, where they're going to be present on other people's skin
as well. And so when we try to use those same methods and techniques, we we are going to be more developing that individual's sweats and oils as opposed to the person who might have touched them that have had done it. So that's always a challenge for us. And that recovering fingerprints from the surface of someone's skin is something that we're just not able to do at this point in time, reliably.
Yeah, exactly. And even a fingerprint on blood is more likely to be smeared, or certainly not a definite definitive. There's my fingerprint. I've put it down and lifted it up.
Yeah. And even a fingerprint in blood is an example. There are different types of ways that that can happen. You can have a fingerprint in blood where there's a blood puddle on a surface and you put it in there, depending on whether it's dry, whether it's still wet, that fingerprint might be removed. We can have it where we deposit something and we deposit our finger first and then blood goes through that. So that's a fingerprint under blood.
And then there's fingerprints in blood where we touch a surface. Get some blood transfer to the surface of our fingers and then touch another surface on top.
That would be the most ideal I think.
Yeah.
And because and then they become visible prints for us because we would be able to see them with the naked eye. We're not we don't need to use methods like powdering to see them. If we want to enhance contrast, we might use special blood enhancing reagents that will again give us a better chance at recovering an identifiable finger mark.
But we should be able to see them. And again, that helps us understand the events that led up to the crime, because in that particular instance, somebody has touched blood. There has to have been blood there for them to.
Touch and.
Identify whose blood that was.
Yep. And we can do, you know, DNA or blood screening to find out whose blood that was. Is it the victim? Is it the suspect? And then we can use those traces to recreate or understand the events that occurred.
So what is new in fingerprint analysis? Do you see it as something that's stagnant, or is there something that is evolving scientifically to improve, being able to detect and lift and collect evidence that's of value?
Um, so while we might think that it's an old school technique, it has been around since the early 1900s. In fact, in New South Wales in 1904, we were one of the first police jurisdictions to use fingerprint identification. So it's very well established how a lot of our methods have come about is through other fields of science or other avenues. So in fact, one of the methods that we use. It's called physical developer actually came out
of photographic development. So when the police were developing their crime scene photos in the dark rooms, they were finding that if they handled certain pieces of paper that they were using to develop the photos, they would also recover their fingerprints as well as develop the photo. So a lot of our methods have come out of, you know, either. Biology, chemistry or other areas. And because we we found that they work we we will use them. So fingerprint research
now it's moved into two main areas. So the first area is around identification. So this is where we will have trained fingerprint experts trying to understand. How they identify an individual, what's their thought processes, as well as the algorithms that we use. When we recover a print we might upload it to, we would call it an alias. So the Australian Fingerprint Identification System, to work on better algorithms, to be more confident with.
How many points of identification, things like how many similarities.
Yeah.
Yeah. So and also what are the elements that factor into an expert making a decision as to whether it's identifiable or not? So you mentioned the number of points in a fingerprint. A lot of countries have moved away from trying to reach. So in some jurisdictions they will say if there are 12 points of identification then that's a they're fairly confident that that is a match. But now most countries in the world try to contextualize that information.
Or just because we if you try to get 12, you're trying to assure an outcome when that outcome may not be. Accurate or appropriate given the evidence that you.
Have on.
CSI. We've always seen them superimpose.
That classic one. Yeah. And then the.
Green matches up and yeah, it looks great for TV, but not necessarily a good outcome for us. So the identification side is one side and then the other side is around detection. So ultimately the goal when we are trying to develop or detect a fingerprint, we are trying to get the best possible image or the best possible developed mark, because the better the mark that we have developed, the more likely that we'll be able to more accurately
and confidently identify a person based on their fingerprint. And so the way that we do that is through new techniques or new methods. Um, so this might be using new technologies or new types of fluorescent powders, uh, new types of chemical detection methods. But then the other side is trying to understand and the fingerprint chemistry itself, so that when we do want to come up with a
new method, what are we actually targeting? How does it work and how can we inform better practice moving forward by understanding what we're trying to detect.
And then to use that you need to do multiple studies have peer review. It's not just a eureka moment.
No. Exactly. Uh, quite a while ago, forensic science was brought into put under the spotlight through two reports from the US. So there was the National Academy of Sciences
report in 2009 and the Pcast report in 2016. And in both of those reports, it really highlighted that in a number of forensic disciplines, there was a lack of scientific underpinning to the work that was going on, and that particular types of evidence should not be used in a court of law without fundamental studies to underpin the
decisions or the outcomes that they were making. So an area was in bite marks, for instance, so that one, as a forensic discipline, has been told to go back to the lab and confirm what you've said is gospel is is appropriate and with some scientific studies. And so fingerprints didn't have the same degree of spotlight on them. But it's always important that we are able to stand by what we do, how we do it, and why
we do it. And the way that we do that is through scientific research and peer reviewed studies.
In terms of fingerprints, it's the biggest thing that people talk about. No one has the same two fingerprints. And I'm always asked by people, but what about identical twins? Would you like to finally address that one, please?
I would.
Love to. Um, so identical twins, when we talk about fingerprints, there are two levels of how we would identify somebody. The first is what we would call the general pattern. So this is the pattern that we can see on the surface of our fingers. And there are three main types of these general patterns. There are what we call whorls. And these look like little circles with larger circles coming from the center. There are loops where we have the
fingerprint ridges coming from one side of our finger. They get close to the center, do a U-turn and come out the same side. And then we have arches, and this is where the ridges will start. On one side of our finger, hit a little bit of a speed bump and continue out to the opposite side of the finger. Now these general fingerprint patterns are passed down by genetics, so identical twins may have the same type of pattern on the same fingers as each other. It's the same
as if your brother and sister. You might also find if you look at your your fingers, you might have the same. I've got a loop on my thumb, you've got a loop on your thumb. And so that's a way that we can classify people or group people into certain areas and exclude people from investigations. If we recover a well at a crime scene and our particular suspect only has loops, well, we can exclude them from further
investigation without going through a full identification process. But what we use to identify people is that while that general pattern is one of those three categories, there's actually smaller minute details that make up this fingerprint pattern. And we call it fingerprint minutiae. Now, why these are very individualizing or why we can say with some degree of confidence that we can identify a person with them, is that
they're actually form randomly. So at the ninth to 10th week of gestation, as our fingers begin to form at that point, they're not fingers, they're the shoulder pads. And. When I begin to form, we will be moving around in the womb and there will be some random interactions with the inside of the womb with ourselves. Or if you have an identical twin, your twin next to you.
And it's the random pressures as your fingers are developing that create these imperfections on the surface of the volar pads.
So it's not blood supply.
Yeah, no, it's to do with how they move around. And and it's these random imperfections that create these minutia that make people, for want of a better term, unique. Even if we cut ourselves or if we, you know, fall over and scrape our hands, the fingerprint ridges will grow back in their original, original patterns if we want to cause permanent damage. We've got to cut several millimeters deep into the skin.
That's incredible. So in terms of gestation, a premature bulb may not have fingerprints evident.
It's very early on. So around that ninth to 10th week of gestation is when that's starting to form. Yeah. And so the information will be there by about week 12. And then it stays that way. And so your fingerprints will stay the same from when you are born all the way until you pass away. They'll get bigger because your fingers will grow over time, but the pattern will remain the same.
So if you have familial patterns, we've heard about familial DNA linking people to crime scenes. Is it possible in the future that you could actually link familial fingerprints?
Uh, so that's not necessarily something that you could do. So while the genetic information will give you that general pattern, as I mentioned, there's only at most eight of these general patterns. And so it's not enough information to say with confidence that we could identify a particular person or
even group them into a familial sort of similarities. Yeah, there are similarities, but yeah, there just isn't enough information at that general level to say with a degree of confidence that that person belongs to that family, because you can go down the street and there'll be people with loops and whorls all on the same fingers that you have, and they won't be related to you.
Does hand sanitizer remove fingerprints of objects?
Uh, yeah, that's a very interesting question. And in a post-Covid world, it was part of our daily life, always hand sanitizing.
And it was it is for some of us. Exactly.
Uh, it's a question that we had actually before the pandemic. Uh, and so we conducted an experiment to see whether different types of hand sanitizers would impact the developed fingerprint, because what we're targeting is often chemical residues. And depending if we have a alcoholic non-alcoholic, the techniques we use can be quite sensitive. So introducing something else might dilute or
potentially damage the fingerprint. So through our work, we took some non-alcoholic hand sanitizers and some alcoholic hand sanitizers and compared uh, we got them to apply the hand sanitizer deposit fingerprints after a certain period of time and then develop them with a range of techniques. And what we actually found was that hand sanitizer has no negative impact
on developed fingerprints. And in fact, non-alcoholic hand sanitizers will actually improve the development for a number of the techniques that we have, and it will actually make it easier for us to recover fingerprints on certain surfaces.
Well. That solved. Yeah.
Myth. Busted.
Myth. Busted. Awesome. Thank you, Scott, so much for joining us today. This has been so fascinating. And fingerprints, everybody seems they know everything about them because I've seen a crime show once and they know they go back to another century. But I just think applying them and learning how you further researching and the science is evolving is fascinating. So thank you so much for joining us today.
My pleasure. It was great to be here. Thank you.
Crime Insider's Forensics is a listener. Original production. It's hosted by me, Catherine Fox, and is produced by Ed Gordon. Sound Design and imaging is by Link Kelly.