GSR Gun shot residue

Gun Shot Residue Trace evidence may be found after a gun has been fired. Trace evidence may be found after a gun has been fired. During this combustion reaction, not all of the material is fully used. During this combustion reaction, not all of the material is fully used. The excess material may be expelled from the barrel, casing, or wherever the smoke and heat escape. The excess material may be expelled from the barrel, casing, or wherever the smoke and heat escape. The material may settle on the shooters hands, clothing or hair and be found at the scene as well. The material may settle on the shooters hands, clothing or hair and be found at the scene as well.

GSR Chemicals are used to react with compounds left by the ignition of the gun powder Chemicals are used to react with compounds left by the ignition of the gun powder Gun powder is made of nitrates Gun powder is made of nitrates Metals (lead and barium) from the primer may also be present Metals (lead and barium) from the primer may also be present These chemicals are what make Gun Shot Residue (GSR) These chemicals are what make Gun Shot Residue (GSR)

GSR You will be using two different chemicals that react with the presence of the products of a fired weapon. You will be using two different chemicals that react with the presence of the products of a fired weapon. Diphenylamine detects the presence of nitrates Diphenylamine detects the presence of nitrates Sodium rhodizonatedetects the presence of lead and barium Sodium rhodizonate detects the presence of lead and barium

What you will do You will test GSR with the two chemicals You will test GSR with the two chemicals You will run a positive control using lead nitrate You will run a positive control using lead nitrate You will then test the unknown for GSR You will then test the unknown for GSR

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

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

A piece of sleeve, around the wrist area, from each individual’s shirt has been sent to you. Your job is to help authorities determine if either had anything to do with the shooting.

What to do Get a piece of notebook paper to record your findings. You will be able to use this paper on your ballistics test. Get a piece of notebook paper to record your findings. You will be able to use this paper on your ballistics test. Your paper should include what makes up GSR and what chemicals are used to detect these chemicals. Your paper should include what makes up GSR and what chemicals are used to detect these chemicals. You will also include the colors of a positive and negative result using these chemicals. You will also include the colors of a positive and negative result using these chemicals.

Make a chart showing the results of everything you do. Make a chart showing the results of everything you do. Label everything clearly so you understand the results of all your tests. Label everything clearly so you understand the results of all your tests. You will first do a positive control test on an alcohol pad using lead nitrate. You will first do a positive control test on an alcohol pad using lead nitrate.

Gun residue presumptive test Open the alcohol pad and put into a petri dish. Place a drop of on two corners of the alcohol swab Open the alcohol pad and put into a petri dish. Place a drop of lead nitrate on two corners of the alcohol swab Place a drop of Diphenylamine on the drop of the lead nitrate. Note that this chemical detects the presence of nitrates from the gun powder Place a drop of Diphenylamine on the drop of the lead nitrate. Note that this chemical detects the presence of nitrates from the gun powder Place a drop of sodium rhodizonateon the other drop of the lead nitrate. Note that this chemical detects the presence of lead and bariumfrom the primer. Place a drop of sodium rhodizonate on the other drop of the lead nitrate. Note that this chemical detects the presence of lead and barium from the primer. Record color changes occurring with each chemical. Record color changes occurring with each chemical.

Expected results Diphenylaminesodium rhodizonate Lead nitratebluered

GSR test on the suspects Now you will test the presence of GSR on the sleeves of the suspects. Now you will test the presence of GSR on the sleeves 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. DO NOT TOUCH WITH YOUR HANDS. USE A CLEAN FORCEP. Obtain a sample of each of one of the suspects sleeves. DO NOT TOUCH WITH YOUR HANDS. USE A CLEAN FORCEP. Add a drop of each of the test chemicals (Diphenylamine sodium rhodizonate) and record your results. Add a drop of each of the test chemicals (Diphenylamine and sodium rhodizonate) and record your results. Repeat with the other suspect. Repeat with the other suspect.

Expected results Diphenylaminesodium rhodizonate Suspect 1Pale yellowLight yellow Suspect 2Dark blueDark red

Your conclusion Remember, neither individual is taking the blame for firing the gun. Are they telling the truth?? Write your conclusion on your paper.