forensic science - gsr trace
When an officer arrives at the location of an alleged shooting, after first rendering aid to the victim, he or she begins to search for evidence. Much of this effort consists of searching for the bullet, the gun, shell casings, and witness testimony; however, when the shooter leaves the scene, he/she takes with them a substantial part of the evidence that can significantly improve the prosecution's case. This evidence can be found on the hands, body and clothing of the shooter. Much of this evidence may be invisible to the naked eye, yet is still valuable for the prosecution's case. This evidence includes micro blood splatter, trace metal evidence, gunpowder residue, and even the gun. The first step when a suspect is apprehended in a shooting is to frisk the suspect for the weapon. While this will display that the suspect has a gun after the approach, it does not assist in the safety of the officer beforehand, nor assist in screening large quantities of people. Being caught with the proverbial smoking gun can be damning evidence in court, but typically at a crime scene, many onlookers gather making the frisking of each individual at the scene or leaving the scene an impossibility. In 1995, the Justice department funde
The first type of evidence the officer can look for is the macroscopic evidence left by the mechanism of the gunshot. These are: blood splatters on clothing, holes and burns in clothing, unburned powder on the hands, and the tell-tale marks from firing an automatic pistol incorrectly. Visible blood splatter should be photographed in the overall, close up, and macro styles both with and without a scale, then collected using a moistened (by means of distilled water) cotton swab then placed in a stopper-less glass test tube and allowed to air dry. This evidence can then be transported to the crime lab for DNA analysis. In addition, known samples of the DNA of both the victim and the suspect should be collected by oral swabs, or other means, and sent to the crime lab in the same fashion. The blood splatter DNA results may prove or disprove that the suspect was in close proximity to the shooting. The splatter pattern may show the proximity and location of the individual to t! Wingate, Anne. Scene of the Crime. Cincinnati: Writers Fisher A.J.,Barry. Techniques of Crime Scene When the suspect is taken into custody, the suspect should not be handcuffed, handled and processed in the traditional means, the suspect should not have their hands cuffed arbitrarily cuffed behind their back as it has the tendency to dislodge gunshot residue form the hands of the suspect. Instead, the suspect should be cuffed with his hands apart, if possible, as to minimize the movement of the hands, which may dislodge the residue from the gunshot. If plastic handcuffs are available, this may be appropriate as so to lend greater credence to the trace metal testing discussed later. In either case, if gunshot residue tests and trace metal tests cannot be performed immediately, the suspect's hands should be placed in paper bags so as to preserve the trace residues left on the hands of the suspect for analysis.2 4 Matunas A., Edward. Lyman Shot shell Reloading Hand Book. ------------------------------------------------------------------------ The final pieces of macroscopic evidence visible on the suspect are injuries incurred on the suspect resulting from misuse of the firearm. These injuries primarily fall into two examples: scope eye and railroad tracks. The scope eye occurs when the scope on a scoped rifle impacts the face of the shooter, leaving the characteristic circular bruising, or even a cut surrounding the eye. Railroad tracks occur when an automatic pistol slide comes back and strikes the hand between the thumb and forefinger. Both of these injuries occur from holding the weapon improperly. See Note 1 Scope eye occurs when the suspect has their eye to close to the scope or holds the gun more loosely. Railroad tracks occur when the suspect holds the pistol too high on the grip and the slide leaves two distinct and characteristic parallel marks between the thumb and forefinger. The presence of these injuries do not implicate the suspect, it merely shows that the suspect sustained similar injuries r!
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Approximate Word count = 2557
Approximate Pages = 10 (250 words per page double spaced)
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