Gunshot Residue Analysis for Law Enforcement – Webinar Series by RJ Lee Group


The following questions and answers are from the RJ Lee Group webinar series, “Gunshot Residue Analysis for Law Enforcement.” This was a two-part series. Day One discussed GSR Sample Collection & Submission, while Day Two will talk about laboratory analysis and testimoney considerations. Day Two’s Q&A will be posted within a few days of the presentation broadcast.

GSR Sample Collection & Submission


What should I do if a piece of clothing that needs to be sampled is almost completely covered in blood?
Be sure to avoid the biological area as much as possible. This may result in a smaller area being sampled. If the items is completely soaked in blood and there is no area that can be sampled, then GSR may not be your best option.

Can you sample from other areas of skin?
Yes, absolutely. Any area of skin that may have been exposed to the GSR is an area that could be sampled.

If the items need additional forensic testing, which test should we run first?
Let’s say a shirt needs to have both GSR and DNA testing. We would want to do the GSR testing first. This is because the DNA swabbing could remove the particulate. In these cases, we make sure to take additional precautions and wear additional PPE, such as a mask, to prevent any biological contamination.

What difference does the number of particle present have?
Whether you have one three component particle or have hundreds, it doesn’t change our conclusions. Day two of the webinar will go over the analytical results and testimony considerations, and will go into greater detail about this.

What is the shelf life of the GSR kit?
The GSR kit doesn’t really have a shelf life. It can be used indefinitely as long as that kit remains closed and not opened.

If someone is forced to use packing tape, how do we want that packing tape to be packaged?
If someone is forced to use packing tape, we really like to see that packing tape put in a tape circle, circled back upon itself and the adhesive used to create a loop. That loop can then be put into a container or a jar, and then sent to us for analysis. But again, if you’re in a pinch, we can get you kits the next day, if needed.

Can you perform distance determination analysis?
Distance determination is slightly difference analysis than primer analysis. That is gun powder analysis, so the science is going to be a little bit different. If you do determine distance determination analysis, that is something our forensics department can do. We do require the firearm that is allegedly used during the incident to conduct that testing.

Day 2 – Analysis and Testimony Considerations


Is it possible to see particles that are NOT round in morphology in a population of gunshot residue?
Yes, it is possible to see some particles that do not have the round or molten morphology in GSR. However, most particles in GSR will have that round or molten appearance.

What type of kit is an Atomic Absorption Kit?
An Atomic Absorption Kit is usually going to contain sampling media that looks like a Q-tip or a swab. This does not look like the SEM stub, which is about the size of a dime, and is a small aluminum pin mount insert that has the adhesive material on it. If you’re using a swab to sample, make sure you get the SEM stubs instead, because that’s what’s going to give you your confirmatory result.

Can you conduct a distance determination test with a firearm to determine the amount of GSR deposited at one foot, three feett, and five feet to show the amount varies at different distances?
This question actually involves powder residue, rather than primer residue. Distance determination analysis involves gun powder residue, which we didn’t cover in this webinar. However, we are planning a future webinar on distance determination analysis.