Transcript Grunge Template - Forensic Science Silpakorn

Gunshot residue
patterns
on skin in angled
contact and near
contact gunshot wounds
PRESENTER: Sommai Sangkaew
51312327
The Importance of
Gunshot Residues in
Forensic
•To identify how the
weapon was use.
•To identify the criminal.
KEYWORD > > > > >
•
•
•
•
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Ammunition
Target
Muzzle-target-angles
Gunshot residues
Powder soot zone
Ammunition
Nitrocellulose (NC-powder)
The Content of a Bullet.
Type of gun
• A weapon that is
used to shoot a
bullet
• Two type of gun:
– Revolver gun
– Automatic gun
Target
an object, usually marked
with concentric circles,
to be aimed at in shooting
practice or contests.
Muzzle-Target angle
• The angle in which
the bullet hit the
target
Muzzle-Target angle (0˚)
MuzzleTarget
angle(45˚)
Gunshot Residues
• Small particles
from the barrel of
a gun when it is
fired
• Consists of:
Primer Gunshot Residue
Particle identified by
Scanning Electron Microscopy
– Antimony(Sb)
– Barium(Ba)
– Lead(Pb)
Powder soot zone
Inner powder soot zone
Outer powder soot zone
PURPOSE
To study the pattern and density
of inner and outer powder soot
zones which occur because of :
• Type of ammunition
• The barrel length
• Muzzle-target angle
• The distance from muzzle
to target.
MATERIAL > > > > >
• Gun
• Cartridges
• Target
MATERIAL >> Gun
1) .38 Smith and
Wesson revolver
2) 9 mm SIG Pistol
P210 automatic
3).22 L.R SIG Pistol
P210 automatic
MATERIAL >> Gun
.22 L.R
.38 Spl
9mm Luger
MATERIAL >> Target
• They used
naturally tanned calf
skin leather fixed on
soap and gelatine
block.
METHODS
Type of gun
Muzzle-target angle
.38 magnum
20, 30, 45,60
-
.38 Spl
9 mm SIG Pistol
20, 30, 45,60
-
9 mm
22 L.R SIG Pistol 20, 30, 45,60
Lengths of barrels ammunition
150, 250, 650
22 L.R
The distance from muzzle to target is 0,5,10,15 and 20 mm
RESULTS
The Inner powder soot
zone can be more
clearly defined and
demarcated than outer
powder soot zone
RESULTS
The Inner powder soot
zones point to the
direction of the muzzle.
RESULTS
When the Muzzle-target
angle is increased, the Inner
powder soot zone will be
wider but the density of
gunshot residues will
decrease
RESULTS
When the length of the
barrel increases,
the Inner powder soot
zone will be denser and
smaller.
RESULTS
When the length of the
barrel increases, the
entrance hole will be
on the rim of the inner
powder soot zones.
RESULTS
The different types of the
ammunitions will result in
different densities of
gunshot residues.
DISCUSSION
• Gunshot residues
on the target surface
can be differentiated
in a inner and outer
powder soot zone
DISCUSSION
• The outer powder
soot zone is much less
visible than the inner
powder soot zone and
may lack on human
skin.
DISCUSSION
•With increasing muzzle
target distance both
inner and outer powder
soot halo increase in
size and decrease in
density.
DISCUSSION
•In angled shots the inner
powder soot halo shows
an eccentric, elliptic shape
which points towards the
muzzle , regardless of
ammunition, calibre and
barrel length.
DISCUSSION
•The outer powder soot points away from the
muzzle in angled contact and close contact shots
SPECIAL THANKS
• T. Plattner , B. Kneubuehi , M. Thali , U. Zollinger ,
“ Gunshot residue patterns on skin in angled contact
and near contact gunshot wounds”
•Associate Professor. Suda Riengrojpitak , Major adviser
• Police Lieutenant Colonel. Suphareark Arepornrat , Miner adviser
• Assistant Professor. Suksiri Vichasri Grams
• Every attendee of the seminar.