GSRGun shot residue

Gun Shot ResidueGun Shot Residue Trace evidence may be found after a gun has been Trace evidence may be found after a gun has been

fired.fired. During this combustion reaction, not all of the During this combustion reaction, not all of the

material is fully used.material is fully used. The excess material may be expelled from the The excess material may be expelled from the

barrel, casing, or wherever the smoke and heat barrel, casing, or wherever the smoke and heat escape.escape.

The material may settle on the shooters hands, The material may settle on the shooters hands, clothing or hair and be found at the scene as well.clothing or hair and be found at the scene as well.

GSRGSR

Chemicals are used to react with compounds Chemicals are used to react with compounds left by the ignition of the gun powderleft by the ignition of the gun powder

Gun powder is made of Gun powder is made of nitratesnitrates Metals (Metals (lead and bariumlead and barium) from the primer ) from the primer

may also be presentmay also be present These chemicals are what make Gun Shot These chemicals are what make Gun Shot

Residue (GSR)Residue (GSR)

GSRGSR

You will be using two different chemicals that You will be using two different chemicals that react with the presence of the products of a react with the presence of the products of a fired weapon.fired weapon.

DiphenylamineDiphenylamine detects the presence of nitrates detects the presence of nitrates Sodium rhodizonateSodium rhodizonate detects the presence of detects the presence of

lead and bariumlead and barium

What you will doWhat you will do

You will test GSR with the two chemicalsYou will test GSR with the two chemicals You will run a positive control using lead You will run a positive control using lead

nitratenitrate You will then test the unknown for GSRYou will then test the unknown for GSR

The scenarioThe scenario

Two individuals were apprehended for the Two individuals were apprehended for the robbery of a convenience store. The store robbery of a convenience store. The store clerk was shot in the torso and later died at clerk was shot in the torso and later died at

the hospital. the hospital.

No gun was found at the scene and No gun was found at the scene and neither individual is taking the blame neither individual is taking the blame

for firing the gun.for firing the gun.

A piece of sleeve, around the wrist A piece of sleeve, around the wrist area, from each individual’s shirt has area, from each individual’s shirt has been sent to you. Your job is to help been sent to you. Your job is to help

authorities determine if either had authorities determine if either had anything to do with the shooting. anything to do with the shooting.

What to doWhat to do

Get a piece of notebook paper to record your Get a piece of notebook paper to record your findings. You will be able to use this paper on findings. You will be able to use this paper on your ballistics test.your ballistics test.

Your paper should include what makes up Your paper should include what makes up GSR and what chemicals are used to detect GSR and what chemicals are used to detect these chemicals.these chemicals.

You will also include the colors of a positive You will also include the colors of a positive and negative result using these chemicals.and negative result using these chemicals.

Make a chart showing the results of everything Make a chart showing the results of everything you do.you do.

Label everything clearly so you understand the Label everything clearly so you understand the results of all your tests. results of all your tests.

You will first do a positive control test on an You will first do a positive control test on an alcohol pad using lead nitrate.alcohol pad using lead nitrate.

Gun residue presumptive testGun residue presumptive test Open the alcohol pad and put into a petri dish. Place Open the alcohol pad and put into a petri dish. Place

a drop of a drop of lead nitrate on two corners of the alcohol on two corners of the alcohol swabswab

Place a drop of Place a drop of DiphenylamineDiphenylamine on the drop of the on the drop of the lead nitrate. Note that this chemical detects the lead nitrate. Note that this chemical detects the presence of presence of nitratesnitrates from the gun powder from the gun powder

Place a drop of Place a drop of sodium rhodizonatesodium rhodizonate on the other drop on the other drop of the lead nitrate. Note that this chemical detects the of the lead nitrate. Note that this chemical detects the presence of presence of lead and bariumlead and barium from the primer.from the primer.

Record color changes occurring with each chemical.Record color changes occurring with each chemical.

Expected resultsExpected results

Diphenylamine sodium rhodizonate

Lead nitrate blue red

GSR test on the suspectsGSR test on the suspects Now you will test the presence of GSR on the sleeves Now you will test the presence of GSR on the sleeves

of the suspects.of the suspects. The suspects are identified as suspect 1 and suspect 2.The suspects are identified as suspect 1 and suspect 2. Obtain a sample of each of one of the suspects sleeves. Obtain a sample of each of one of the suspects sleeves.

DO NOT TOUCH WITH YOUR HANDS. USE A DO NOT TOUCH WITH YOUR HANDS. USE A CLEAN FORCEP. CLEAN FORCEP.

Add a drop of each of the test chemicals Add a drop of each of the test chemicals ((Diphenylamine Diphenylamine and sodium rhodizonate)sodium rhodizonate) and record and record your results.your results.

Repeat with the other suspectRepeat with the other suspect..

Expected resultsExpected results

Diphenylamine sodium rhodizonate

Suspect 1 Pale yellow Light yellow

Suspect 2 Dark blue Dark red

Your conclusionYour conclusion

Remember, neither individual is Remember, neither individual is taking the blame for firing the gun.taking the blame for firing the gun.

Are they telling the truth??Are they telling the truth??

Write your conclusion on your paper.Write your conclusion on your paper.