After the Webinar: Mythbusters! The Value of Negative Testimony in Forensics. Q&A with Andrew Reitnauer

Webinar presenter Andrew Reitnauer answered a number of your questions after his presentation, Mythbusters! The Value of Negative Testimony in Forensics. Here are just a few of his responses.


Audience Question: How do we help jurors understand that Hollywood really is just make believe without sounding like we’re copping out or making excuses when we’re on the standards, and realistically what the jury expects is just not feasible?

Andrew Reitnauer: Really, the one way that I have found success in doing it, and I don’t usually kind of address the Hollywood aspect of it. I kind of stick more to the actual science I’m there to present. And I try and present that information in a very structural way and starting off with a lot of that foundation but speaking in a way that everyone can relate to and understand. So, when you are talking about types of evidence, you know, mentioning certain types of items that everyone would be familiar with. When you talk about things like, “What is a fingerprint?” Don’t be afraid to talk with your hands a little bit. And, you also have to be able to read your jury. One of the things, and I’ve testified as an expert probably over 100 times now at this point in my career. But I’ll often watch the jury while I’m speaking, and you should always address your answers to them anyway. But also, in more of a psychological way, trying to read your jury. Because when I’m talking about what is a fingerprint, I always say to people, the first time I see one juror look at their hands, I’m on the right wavelength if you’re understanding what I’m talking about. So then stay on that wavelength.

And be able to talk about a lot of these different topics and about your examination method in that same kind of level, because they’re understanding what you’re talking about. If you get very technical about a lot of things, you’re going to kind of lose people, because they don’t understand a lot of the scientific fields the way that we do. Just being able to explain things in a very face value way, showing that this is the way we actually do things in the laboratory, this is my process, this is my examination method, this is what I’m looking at, it really seems to help. When you start to see those head nods and things like that. You do know that people are understanding the questions that you’re being asked.


Audience Question: Is it possible to extract DNA from a fingerprint? 

Andrew Reitnauer: Absolutely. And most of the laboratories I’ve worked that, when we’re doing our visual examinations to begin with.

So, we’ll just use a firearm, as an example, because it’s good item to use for an example. We’re looking at it first to verify any serial numbers, identifying information, things of that nature. Your visual exam is also looking for any trace evidence, if there’s any blood present, if there happens to be any patent detail or latents that are reacting naturally with your light that you can photograph first. But also, a lot of laboratories will take touch DNA swabs from the very beginning, and those swabs would be taken from areas where it’s likely someone may have held the item or touched an item but, they’re not so conducive for prints. So, again, using a handgun is the example. You’re grips are going to be very textured. That’s not a great surface for, for latent prints. So, taking a swab from the grip potentially, the trigger, although I have gotten latent prints on the triggers. So that’s up to you, your discretion. And also, on the slide there’s a lot of grooves or someone who’d grip it to retract the slide On a semi-automatic handgun. That’s a great surface, because you have to really exert some force for that motion. And those little grooves could really strip off some skin cells. So, you can take those swabs before your examination, because they’re really not going to have a huge impact on the following sequential methods when you actually process it for latent prints.


Audience Question: Will reagents impact the ability to extract that DNA? 

Andrew Reitnauer: Most of them do not. The problem is most reagents are liquid, and when you employ a liquid reagent onto an item, you do have that physical process of spraying or dipping or cascading that reagent over the item which could wash away any skin cells that are present because it is fragile.


Audience Question: Are toe prints the same as fingerprints? 

Andrew Reitnauer: Yes, they are. We have friction ridge formations, both on the palms of the hands and the soles of the feet. That’s kind of a consistent characteristic among primates. And it’s primarily form when we look back physiologically for tactile grasp. So, the reason we can hold on to our, or soda cans is because of the presence of friction ridges. And if you think about primates that live out in the wild, when they’re gripping branches of trees and things like that, that’s one of the reasons that they’re able to do so is because of the friction ridges on the palms of the hands and the soles of the feet. So, if you do have known plantar impressions or foot impressions from someone, you can absolutely conduct an examination, a comparison between a footprint, and their known footprint.


Audience Question: Can AFIS capture and store the search for toeprints? 

Andrew Reitnauer: That database has not been developed yet. Normally, in any case that I’ve been involved in, that requires the comparison of toe prints or footprints with the friction ridge skin, that’s a special request to get someone’s known footprints.


Audience Question: As a prosecutor, what’s the best way to handle a defense expert whose conclusions are different or differ from those of our own lab?

Andrew Reitnauer: I would imagine, the best way to do it is sort of what we would do in the laboratory of this situation were to occur? And then I would compare it in terms of, say your initial examiner says, it’s an identification, and your verifiers says, it’s an exclusion. Normally that’s going to go through conflict resolution, so you have a third party that’s going to independently examine the evidence. From the perspective of it occurring at the trial phase. I mean, you’re obviously past, you know, the laboratory phase at that point. It really, I think, would come down to people being able to present the data they used to arrive at their conclusion. And if, say examiner A, had their results subjected to blind verification, which is another quality assurance measure, that may strengthen that conclusion a bit versus an examiner who simply on their own arrived at a conclusion without any secondary verifications. So, there are some considerations with that. However, there can be a lot of documentation to help demonstrate what led to the conclusion being rendered in forms of digital images, annotations, the creations of those charts, per se, things of that nature. And there, there’s even further ways to start showing confidence and marking distortions. There’s a whole different spectrum of documentation when it does lead into those comparative methods.


Click Here to Watch a Recording of Mythbusters! The Value of Negative Testimony in Forensics. 



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