Gunshot residue

patterns on

skin in angled

contact and near contact gunshot wounds

PRESENTER: Sommai Sangkaew

51312327

•To identify how the weapon was use. •To identify the criminal.

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2

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The Importance of Gunshot Residues in

Forensic

• Ammunition• Target• Muzzle-

target-angles

• Gunshot residues

• Powder soot zone

KEYWORD > > > > >

Ammunition

Keyword

The Content of a Bullet.Nitrocellulose (NC-powder)

Keyword

• A weapon that is used to shoot a bullet

• Two type of gun:– Revolver gun– Automatic gun

1 2

1: Revolver2: Automatic

Keyword Type of gun

Keyword Targetan object, usually marked

with concentric circles, to be aimed at in shooting practice or contests.

• The angle in which the bullet hit the target

Muzzle-Target angle (0˚)

Muzzle-Target

angle(45˚)

Muzzle-Target angle

• Small particles from the barrel of a gun when it is fired

• Consists of:– Antimony(Sb)– Barium(Ba)– Lead(Pb)Primer Gunshot Residue

Particle identified by Scanning Electron Microscopy

Gunshot Residues

Outer powder soot zone

Inner powder soot zone

KeywordPowder soot zone

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.

PURPOSE

MATERIAL > > > > >

• Gun• Cartrid

ges• Target

1) .38 Smith and

Wesson revolver

2) 9 mm SIG Pistol

P210 automatic3).22 L.R SIG Pistol

P210 automatic

MATERIAL >> Gun

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2

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.22 L.R

9mm Luger.38 Spl

MATERIAL >> Gun

• They used naturally tanned calf skin leather fixed on soap and gelatine block.

MATERIAL >> Target

Type of gun

Muzzle-target angle

Lengths of barrels

ammunition

.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

150, 250, 650

22 L.R

The distance from muzzle to target is 0,5,10,15 and 20 mm

METHODS

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.

RESULTS

• 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

DISCUSSION

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.