‘Green’ ammunition - gunshot residue analysis video transcript
I wanted to take us back to what forensic science is all about really. It is about traces. That's what forensic scientists tend to obsess over, these tiny little remnants of activity. It's about understanding why they're there, how they arrived there, and also performing comparisons between samples that you might collect at a crime scene and from a potential suspect.
These are the traces that we're interested in. You might think, well where do they come from? How have they landed where they find themselves? This gentleman, Edmond Locard, put together - it's called the Locard's Exchange Principle. It describes that process of when there is contact between two things, two people, there will be an exchange and it's those traces that we then seek to uncover.
I do like that image of Locard there. It's almost as if he's going, it was that guy. Obviously a big player in the development of our understanding of the role of traces.
Gunshot residues - they're just one of the traces that we're interested in analysing. You might think, why are they important? Why is gunshot residue important? I don't think I have to show too much data to explain that, but this is a slide identifying just in the Sydney metropolitan area the number of shooting-related incidents. Over that two-year period there have been 260 individual incidents, some of them fatalities, some of them involving injuries, others no injury but still an incident to report.
We've been absolutely bamboozled with newspaper reports and stories around Australia facing the new gun crisis and all the inroads that we made with the buyback being rolled back. Loads of different reports out there. So I don't think the idea of gunshot residue analysis being important - hopefully you're convinced.
Just to step back and think well where does gunshot residue come from? Where does it arise? What we've got up on the screen - it is the only slide I have with white on it, I promise you. I presented last night and blinded the entire audience with a couple of slides, so I learnt from that.
What we've got down in that bottom section there of the cartridge case is the primer. That's where everything starts, from there. We then have the internal casing area, which is where our propellant is housed. Right at the top of the cartridge case is the bullet.
So what we end up with is, from those various components, during the firing process residue is produced. It can be deposited on the hands; it can be deposited on the clothing of the shooter.
Another little cross-section just showing that process. We have a firing pin in the weapon. It strikes the primer. That primer will then undergo ignition. That ignition will then cause all of that propellant, which is in the central cavity there, to also ignite. Massive amounts of pressure are built up and that ejects the bullet from the case so it will travel down the barrel of the weapon.
We're interested in both the residue that's generated from the primer and also the residue that's generated from the propellant. They're two different types of residues, but both very important.
There will not be a pop quiz on all of these compounds, I promise you, but there are a huge number of different compounds that arise from the propellant. Not as many in the primer area, but obviously they're all of interest to us.
Firstly we'll start to talk about these compounds that are in our primer. That's what we refer to or they give rise to inorganic gunshot residues. The others, they're known as our organic gunshot residues, the difference being the inorganic residues contain metallic components, the organic ones non-metallic. We can analyse those in different ways and we have to consider both of them when we're thinking about sampling and analysis.
If we are starting with those inorganic residues, they're the ones that over time, that's what we traditionally have analysed when we're looking at gunshot residues. There's a particular technique we use. It's called scanning electron microscopy with an EDS detector. That particular technique is, as I mentioned, using the inorganic residues. There are three different reasons why we love this technique. It is the international choice that everyone is using for gunshot residue analysis.
It gives you elemental composition information. That primer down the bottom has got things like lead, barium and antimony. We can identify those particular elements. You can see here one of the results that we would generate, the spectrum we would generate. There are those elements circled.
We also get morphology. It's this beautiful, spherical particle which is a really good indicator that we have a gunshot residue particle.
The other reason is, it's non-destructive. We love that in forensic science. Anything that is non-destructive is fabulous, because it means we can come back to it should the need arise.
Now let's think about some of the current challenges. That's not all of them. There are lots of them. We could have people working on projects in all of these different areas, because there are some issues around the interpretation of gunshot residue analysis.
One that I've left off, and I say deliberately, is a case that people may have heard of. It was the Eastman Inquiry. It's only recently been resolved. The case involved David Eastman. He was accused and in the trial found guilty of shooting Colin Winchester, who was the assistant commissioner of the AFP at the time. This was 1989, so we're talking quite a while ago.
One of the issues in that case was the forensic evidence. The forensic evidence in that case involved gunshot residues. You may be thinking, oh, is the future really about gunshot residues? Are they not a flawed piece of evidence? But in this case, it wasn't really the actual evidence itself; it was the way in which it was presented by the forensic scientists.
I had a lovely discussion - we were at an international conference last week. The international conference was in Adelaide. I know that seems - it's not exactly international to go to Adelaide, but lots of international delegates. A lot of people going, oh, is gunshot residue analysis finished, done, dusted? No. The actual techniques and the principles and what we can extract from gunshot residue analysis are alive and well. What we have to watch out for is when rogue scientists will go beyond their areas of expertise, which is exactly what happened in this case.
I won't say the jury's out. I think the jury's in on this case. There's a lot of circumstantial evidence, but it was quashed based on the forensic evidence that was put forward.
So I've left that off that list, but the one we're going to talk about a little more tonight is the impending or the potential for the increasing prevalence of lead-free ammunition. This is the going green. No, it does not mean that the ammunition will end up with green tips. This is actual ammunition. You can see it flying through. It doesn't mean that it's going to look like this. What it means is, we're taking the lead out.
So in that primer down at the bottom of the cartridge case, they're now going to be lead-free, barium-free ammunition. So suddenly, if the things that we needed to identify that as a particular particle of gunshot residue have been taken out of the formulation, really we're not going to be able to rely on this technique.
Gunshot residue - the lead-free ammunition is not coming - it's not going to take over the world any time soon, but what this project and what the research team are working on is about future-proofing gunshot residue analysis.
The overall aim of the project is about developing protocols that will allow us to integrate the analysis of the organic gunshot residues. If we can no longer rely on the presence of the inorganic, let's rely on all of those compounds in that huge table that are present in the organic.
There's going to be a period of time where we'll be able to find both, so let's bring them together. Let's see what additional information we can get out of bringing those two forms of analysis together, but let's also future-proof when lead-free ammunition becomes more prevalent.
I'm going to touch on some of the results that the research team have been working on. I'm one of a group in this area. We had a wonderful PhD student, [Varina] - I think she is out there; I think I can see her - who is working in this area. We also had [Maria Morellato], who's been working on one of the aspects. Honours student, Stephanie [Tann], Anthony [Ogul]. It's been very much a group effort.
So here in these various project sections, the first that we're going to talk about is the evaluation of the different techniques that we had available to us. We're focusing on the organic compounds. Here are a couple of options that we can use.
The first of them is ultra high pressure liquid chromatography. Essentially we take a complex mixture and we're able to separate it into all of the different components. Varina has worked on - and I mentioned it at the conference last week - this is months of work and what I've done is condensed it on to one slide. I'm sure that's making her very happy, but it was a whole lot of work to generate results like this. Each of those little peaks represents a different compound. These are all target compounds in the organic gunshot residue.
The other technique that we've been evaluating is called desorption electrospray ionisation mass spectrometry - DESI MS, because it's a whole lot easier to say that. With DESI, what we're doing is the little brown tube that's coming in at the top of the instrument that is firing a charged solvent line at the sample. The sample in this case is our white tablet there. That charged solvent line ionises the sample, because that's in important step with mass spectrometry. It then desorbs the sample off the surface and that's transported into the mass spectrometer.
This is a technique that requires very little sample preparation, and that's something that we love. Very easy to just bring the sample on to the sampling area and analyse.
In terms of the workflow, Marie was working on this particular project. What we've identified is a bit of a workflow. We're still working on this technique. We have Stephanie, an honours student who is continuing the work in this area, but the first step is analysing the unfired propellants. That allows us to identify the target compounds of interest.
We then get to go to the range, because it's always fun to shoot guns. We then get to sample. That's the important step. We then bring it back to the lab, conduct the analysis using what we're proposing as a technique that we can integrate, and then off to what we call the traditional method, which is the SEM/EDX analysis.
What we're doing here is, we're sequencing both the organic and the inorganic. It was very important for us to establish, do they work in sequence? Does the analysis by DESI preclude the future analysis via SEM/EDX? The answer was no, they can exist together.
So where we were able to identify organic components on the post shooting samples, we were able to find the characteristic particles.
There was an exception there. Obviously we did trial some lead-free ammunition and we weren’t able to find these particles, again demonstrating why there is that need to look at a technique for the organic analysis.
The next step we've been looking at is the sampling. If we come back to where forensic science starts, it's all about the trace. We need to be able to sample those. We need to be able to detect them at the crime scene and either do analysis at the scene or bring them back to the lab. So sampling is absolutely critical.
There are three different protocols being evaluated at the moment. One of those involves swabbing the hand with an alcohol wipe. It then allows you to take it through an extraction step and then a filtering step which will allow for both the organic and the inorganic analysis to take place.
The second process - that uses the traditional stubs that you can see up there in the top corner. They've got an adhesive layer. They're really good. You just dab them along the hand and pick up any of the residue that is left.
Another technique which is called solid-phase microextraction - this is where again we use the standard stubbing. We then expose this little fibre, and it's just - you can see the fibre protruding into that small vial. It then absorbs the compounds of interest. These are our target organic compounds. We can then perform SEM analysis then the organics. All of this is working towards understanding how we can sequence these techniques better.
In summary, we've had the shooting incident. We have to think about the best way to sample those residues, then what technique is best to use, and then again, how do we bring those two datasets together? Perhaps in the future we may not have the bottom dataset; we may only have the organics to rely on.
As we've seen, things can happen in the lab, but we also need to take them out to in this case the field. The field was an indoor range for us. The preliminary results that we've looked at, it's fine to simulate things in the laboratory setting, but we have been able to detect the organic residues using the protocols that have been developed. So that's the first step. Well, I guess we're a little way in, but it's one of the steps that we're taking towards identifying what that optimal protocol is.
I'd like to finish with some acknowledgments as well. We have a wonderful research team working in the Centre for Forensic Science that I have mentioned: Claude Roux, who is our director for the Centre for Forensic Science, and another collaborator at Flinders University, who was previously with the AFP.
That I think is one of the things that defines what UTS research is all about. It's the fact that we do collaborate. I think that brings a whole wealth of knowledge and a different perspective on our research challenges.
I thank you for your attention. I think we're all going to be coming up on stage for some questions. Thank you.
11 September 2014
Test Tags: green ammunition, gunshot residue, trace metals, forensic techniques
Gunshot residue analysis can provide valuable information about whether somebody has recently discharged a firearm. However, concern over the health and environmental impacts of heavy metals has seen an increase in the prevalence of lead free ammunition.
This has the potential to compromise the effectiveness of current forensic techniques for gunshot residues analysis which target the metallic components of ammunition such as lead.
Dr Alison Beavis will discuss current research exploring a range of methods and techniques that have the potential to be used when lead free ammunition is encountered in forensic case work.
UTS Science in Focus is a free public lecture series showcasing the latest research from prominent UTS scientists and researchers.
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