This presentation is a brief about how the Gun Shot Residues are forensically examined.

2.  Introduction
 History
 Where we found GSR?
 Pattern of GSR
 Composition of GSR
 Problems which can be solved by GSR
 Collection of GSR
 Detection of GSR

3.  GSR stands for ‘Gun Shot Residue’ , also
known as cartridge discharge residue (CDR),
"gunfire residue" (GFR), or firearm discharge
residue(FDR)
 It is a residue deposited on the hands and
clothes of someone who discharges a firearm.
It is principally composed of burnt and
unburnt particles from the explosive primer,
the propellant—and possibly fragments of
the bullet, cartridge case, and the firearm

4.  In 1971 John Boehm presented
some micrographs of gunshot residue
particles found during the examination of
bullet entrance holes using a scanning
electron microscope.
 the chemical elements present in such
particles, mainly lead, antimony and barium,
can be identified.

9.  Has the given gun been fired?
 Has the given projectile or the cartridge case
been fired?
 Did the suspect shoot? In fake suicide cases
the question may be crucial.
 Is the given wound a firearm injury?
 Is the given hole (on clothes, furniture, walls,
etc.) a gun shot hole?
 What was the firing range?

10.  Gunshot residue are complex mixture of
materials produced in the gunshot firing.
Their composition is depend on following:-
 1. The nature of the formulations of the
propellants and primer mixtures.
 2. The composition of the projectile
materials.
 3. The barrel scrapings.

11.  Black powder Residue
 Smokeless powder Residue
 Organic components: Nitrocellulose,
Nitroglycerine, DPA (Diphenyl Amine), etc.

12.  The Gun shot residue are collected by
numbers of method:-
 Dry method
 Wet Method
 Collection of organic residue:
 > Swabbing
 >Tape lifting
 > Vaccum lifting

13.  The following techniques for the detection are in
famous to supplement visual examination:
 Infrared rays photography is useful especially in
case where GSR are on colored clothes. They
reveal pattern.
 X-rays fluorescence reveal lead and other
particles present in the deposited GSR from
primers.
 SEM has been found exceptionally useful not only
to detect GSR but also it can give size and
number of particles.

14.  Dermal nitrate test: It was used prior to 1950
to identify the shooter. The nitrate are picked
up on a paraffin wax cast as described earlier,
the picked up residue on the cast are treated
with diphenylamine dissolved in strong
sulphuric acid. The appearance of blue colour
spots indicates nitrates, they are indicative of
GSR

15.  Walker’s Test: A piece of filter paper is
moistened with acetic acid. It is pressed
against the target surface and it pick ups the
GSR. The filer paper is then sprayed with a
solution of 2 naphthylamine sulphuric acid
and citric acid. The pink colors specks
indicates nitrite particles , they indicates GSR

16.  Harrison and gilroy’s test: Cotton swab was
dipped in 0.1N HCl and then applied on shooters
back of thumb trigger finger and web of palm, 2-
3 drops of triphenyl methyl arsonium iodide
solution is added to the cotton, if orange colored
ring is formed then antimony is present. After
drying it for 2-3 minutes,5% freshly prepared
sodium rhodizonate solution is added, if red
colour appears, the barium or lead is present.
 Let it dry and add 1:20 HCl. If red colour changes
into blue , then lead is present and if red colour
is retained , then barium is present.


17. 