1

Gun Shot Residue (GSR)

Residues from explosion

of primer and charge

GSR

2

Deposited near the discharged weapon

Hands and clothes of gun man

Clothes of target

Gun Shot Residue (GSR)

Spreads out a distance of 1 m

3

If the gun is pressed

against victim’s head

Head wound

Gun Shot Residue (GSR)

GSR forced

into wound

4

How can we detect GSR?

Gun Shot Residue (GSR)

Nitrite residues

Nitrate

Nitrocellulose

Nitro glycerine

3 inch Griess test results

5

Griess Test

Test for nitrite

(X NO

2

) residues

6

Griess Test

Fertilizers

May give false positive due to

Urine

Cosmetics

Tobacco

7

Birmingham Six

Wrongfully convicted of carrying

out IRA pub bombings in 1974

Based in part on a Griess test

Conviction overturned in 1991

8

Sodium Rhodizonate

Test for lead, barium and

antimony from the primer

Sodium rhodizonate

9

Sodium Rhodizonate

Detection of barium, lead and antimony

Most probably GSR

10

SEM-EDX

SEM

See GSR particle

GSR particle

EDX

Tell what elements are present

11

1999

Jill Dando shot

on her doorstep

Jill Dando

Barry George

12

Barry George

Arrested, charged

and convicted in 2001

One particle of GSR

found in his coat pocket

13

Barry George

Deposited GSR only lasts for a few hours

Released on appeal in 2007

GSR particle trapped in his coat pocket

GSR evidence unreliable

14

GSR

GSR cannot be individualized

Not much variation within GSR

15

Types of GSR

Lead, barium, antimony

Lead, barium, antimony, aluminium

Lead, barium, antimony, tin

Lead, barium, calcium, tin, maybe antimony

Barium, calcium, silicon, tin, maybe lead

4

2

1

5

3

16

Summary

Comparison of firing pin marks

Comparison of bullet striations

2

1

Detection of GSR

3