How do they test for gunshot residue?

Asked by: Valerie Moore

Gun shot residue is tested by lifting samples off a defendant’s hands or clothing and then testing to see if the lifts contain a fused particle of barium, antimony, and lead, which are known to be present in GSR.

What is used to detect gunshot residue?

A simple method for detection of gunshot residue particles from hands, hair, face, and clothing using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX)

Can you wash off GSR?

Washing the hands is likely to remove all GSR. o Do not routinely sample victims of gunshot wounds. The presence of GSR indicates that a person has been in an environment containing GSR.

What is the name of the test used to test for the presence of gunshot residue?

Compiled by Don Penven. Gun Shot Residue, or simply GSR, is a means of testing for the presence of certain materials on the hands and clothing of a subject in hopes of determining that this individual may have discharged a firearm. The concept is an old one and dates back many years.

How long does GSR last if found on a living person?

4–6 hours

Gunshot residue is the consistency of flour and typically only stays on the hands of a living person for 4–6 hours. Wiping the hands on anything, even putting them in and out of pockets can transfer gunshot residue off the hands.

How is GSR tested in the crime laboratory?

A typical GSR collection kit contains adhesive disks to sample an individual’s hands. The adhesive disks are analyzed directly using scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX).

How long does GSR stay on clothes?

Remember that traces of gunpowder residue can be found on clothing or skin, as well as on the surface, for up to 78 hours after firing a firearm.

Are GSR tests reliable?

GSR tests results are considered reliable, and should be admitted into evidence. Gunshot residue can be removed by actions such as washing hands, wiping clothing, or brushing it off, so the absence of residue does not prove that the person did not recently fire a gun.

What are the three most common trace elements found in gunshot residue?

The stubs of the gunshot residue kits are analyzed for constituents of gunshot residue, namely the elements lead (Pb), antimony (Sb) and barium (Ba). These three elements originate from the primer of most firearm cartridges.

What is gunpowder residue test?

Gunshot Residue Tests

Detection of GSR has two primary objectives: (1) determining if an individual fired or handled a recently discharged firearm or if a surface was in close proximity to a weapon during discharge; and (2) analyzing the pattern of GSR for the purpose of determining the muzzle-to-target distance.

How long does a gunshot residue test take?

30 to 40 minutes

“Gunshot residue tests are done in almost every case where a shooting has taken place,” Burleson said. “The main focus of our research is to develop a method that will help credibility of gunshot residue evidence in court. You can get results with this test in 30 to 40 minutes with the new test.

What substances might cause a false positive GSR test?

Samples collected from occupations or simulations thereof include welding, pyrotechnics, key cutting, mechanics, and paper products all of which produced significant false positive results for gunshot residue.

How is gunshot residue used in forensics?

The examination and analysis of GSR on items of evidence can allow determinations to be made as to weather a hole or defect is consistent with being caused by a bullet (or other firearm-related projectiles).

Which technique of detecting gunshot residue holds the most promise for the immediate future?

Which technique of detecting GSR holds the most promise for the immediate​ future? The distribution of gunpowder particles and other discharge residues around a bullet hole​ permits: Determination of the distance from which the gun was fired.

What chemicals make up GSR?

GSR consists of unburned or partially burned gunpowder particles, soot, nitrate, and nitrites from the combustion of the powder, particles of primer (oxides of lead, antimony, and barium), and particles of the bullet or the bullet jacket that are vaporized when a firearm is discharged (Rowe, 2000).

How is paraffin test conducted?

The test was performed by covering a suspect’s hand with a layer of paraffin, which, after cooling, could be broken off and the paraffin treated with an acid solution of diphenylamine, a reagent used to detect the presence of nitrates or nitrites. A positive result would then be read as blue flecks on the wax.

What are the different qualitative test for gunshot residue?

The scanning electron microscope method using X-ray analysis is considered the most reliable and useful way to test for gunshot residue because it can detect any type of element, ion, or compound. This testing procedure is especially helpful when used to confirm the results of one of the other GSR chemical tests.

Is paraffin test acceptable in court?

All other matters, such as the paraffin test, are of lesser consequence where there is positive identification by the lone eyewitness, Leo Mirabueno, of appellant as the perpetrator of the crime. Hence, a paraffin test cannot be considered as conclusive proof of appellant’s innocence.

What is dermal nitrate test?

known as the dermal nitrate test or diphenylamine test. The procedure tests the presence of nitrates and nitrites that may have come from gunpowder or primer inside the bullet casing that ignites when a gun is fired. This procedure involves coating the subject’s hand with melted paraffin wax.

What is paraffin test?

Definition of paraffin test

: a test in which a paraffin cast of the hand of a person suspected of firing a gun is subjected to chemical analysis to determine the presence of powder particles.

What is sodium Rhodizonate test?

The Sodium Rhodizonate test provides a color reaction indicative of the presence of lead. It can be employed around the periphery of a hole or defect to determine if it is consistent with the passage of a bullet.

What is the positive result for the dermal nitrate test?

A positive reaction indicating the presence of gunpowder residues is indicated by the appearance of dark blue pin-point specks on the inner surface of the cast.

Which material can give a false positive for the dermal nitrate test?

Substances when present on the hands of the deceased which are commonly found and are known to give a positive reaction to the diphenylamine test are as follows: Tobacco or tobacco ash, fertilizer, pharmaceuticals, leguminous plants, urine, etc.

When did GSR testing start?

19331

Initial literature searches found that laboratory solutions to this problem have been around for decades, with forensic tests for gunshot residue (GSR) published as early as 19331.