GSR Collection Considerations for Investigators

When there is suspicion that a firearm has been discharged, the collection of samples for GSR analysis must be performed carefully best ensure the recovery of potential particulate. Before collecting any samples, there are a few considerations to keep in mind for the best chance of success.

GSR Sample Collection Checklist

Before collecting any samples, there are a few considerations to keep in mind to give you the best chance of success. 

Time/Activity: As time passes from the moment a firearm incident occurs, the subject containing potential GSR particles can shed particles as a result of their movement and activity. Whenever possible, obtain samples from subjects as soon as possible and prevent them from activities such as washing hands and changing clothes.  

Bagging of Subject Hands: If collection cannot be done at the scene it is highly recommended that the subject's hands be bagged before being handcuffed.  This is done to prevent potential contamination. 

Preservation of Clothing: Do not place all of a subject’s clothing into a single evidence bag. All items of clothing should be packaged individually for analysis so no cross-contamination occurs. 

Preservation of Clothing: Do not place all of a subject’s clothing into a single evidence bag. All items of clothing should be packaged individually for analysis so no cross-contamination occurs. 

Contamination: Police officers who collect GSR samples from subjects need to be especially cautious as they and their surroundings can already contain GSR.  Anyone who recently handled or discharged a firearm should not perform the collection. To further minimize the risk of contamination, the collecting officer should wear clean gloves and be aware of potential contamination sources around the collection area.

Occupation of Subject: It is important to note the occupation of a subject as some lines of work can have the potential to deposit similar particles to those found from the discharge of a firearm.

Prior Activity of Subject: It is important to note the prior activity of a subject.  For example, if a subject had been at a shooting range earlier in the day, it may not be unusual if GSR is on them.

Collecting Samples

When collecting samples for potential GSR, it is important to use the proper collection techniques. Scanning Electron Microscopy (SEM) kits that utilize adhesive stub samplers are the current best method of GSR collection. These kits can be purchased from RJ Lee Group if needed.

Hand Sampling

• When collecting samples from hands, request Product # GSR-SEM: Gunshot Residue Collection Kit for Hands and Skin which includes pre-labeled stubs that make collection clear and straightforward.
  
  
• Samples collected from the back of the hand should focus around the thumb and forefinger and the webbed area in between. Once that area has been sampled continue sampling the remaining portion of the back of the hand including fingers.
  
  
• Samples collected from the palm should focus on the large portion of the palm first. Once that area has been sampled continue sampling the remaining portion of the palm including fingers.
  
  
• If particle extraction cannot be performed on a suspect near the time and place of a firearm discharge, the suspect's hands should be bagged until sampling can be performed.

Fabric and Clothing Sampling

• When sampling fabrics or clothing, request Product # GSR-SEM/SUR: Gunshot Residue Collection Kit for Fabrics and Surfaces which contains multiple stubs because they will lose their adhesive ability as they are used over large areas like articles of clothing and multiple stubs are generally required.
  
  
• When sampling articles of clothing it is best to first divide the item into sections before collection.
  
  
• Collect in both a horizontal and vertical direction to ensure the entire surface has been processed.
  
  
• If there is any concern over proper collection techniques, each item of clothing or fabric should be individually bagged and sent to RJ Lee Group for professional particle extraction.

Vehicle Sampling

• When sampling vehicles, request Product # GSR-SEM/SUR: Gunshot Residue Collection Kit for Fabrics and Surfaces.
  
  
• Consider the flow of an incident before collecting samples from a vehicle. For example, if a shooter discharged their firearm out the driver's window, you would collect samples from the driver’s door before you collected samples from the passenger seat.
  
  
• Areas for collection in a vehicle include but are not limited to:
  
  
  • Seats (cushion, backrest, and back of seat)
  • Headliner
  • Door paneling
  • Center console
  • Dashboard
  • Steering wheel
  • Gear shift
  • Outer portions of the vehicle

RJ Lee Group

RJ Lee Group routinely works with over 400 law enforcement agencies, prosecutorial attorneys, and defense attorneys throughout the United States and around the world. Our analysis helps provide answers to our clients, and RJ Lee Group’s team of expert witnesses gives those answers a confident voice by communicating complex scientific concepts clearly in court testimony.