The Main Aspects Of Evidence Collecting At A Crime Scene

The technique used in ballistic testing and analyzing the theory is that firearms produce unique markings inside the barrel. Ballistic examiners research the variations of ridge shapes typically called striations, patterns, looking for certain points of uniformity to form a match. To finalize the conclusion a second ballistic examiner would confirm the test by conducting the same test and retrieving the same result. Ballistics are like fingerprints, no two are alike.

Trajectory analysis is not an accepted scientific test because it is not an exact test, it is considered a good reference. It is an approximate based on the facts it would be impossible to determine the exact point a perpetrator was standing but based on the scientific evidence you could approximate the location.

There are guidelines in collecting evidence depending on what samples are being collected. All samples collected are stored in separate containers, glass vials are only used when there is nothing else available. When preserving fingerprints by using gloves or white handkerchiefs, limited contact is always recommended.

Controlled substances have potential to leak or spill and should be packaged in heat sealed Kapak bags a GSR kit would be used in collection of gunshot residue, it should be collected as soon as possible due to the fragility of the residue. Clothing and material should be carefully folded and wrapped in clean paper to preserve the residue. It is important to collect all ammunition and casings and label separately in pill bottles or envelopes. It is important to never label the bullets, a loaded firearm should never be admitted into evidence even if it is not cocked or with the safety on.

Flammables such as liquids should be placed in a glass vial with an airtight seal to avoid evaporation of wood, cloth, or paper can be placed in metal cans to prevent evaporation. At burglary paint and tools can be present, care is taken to preserve paint, possibly on the tool by unwrapping the end in paper and taping it to avoid loss of paint evidence. Large glass windows or fragments are placed in boxes or film cans. If hair or fibers are present they can be removed by using tweezers, they should be placed in proper envelopes which should then be placed in a large envelope. Seminal stains should be allowed to dry as with all moist stains, they should be placed into paper bags (never plastic). Handle these samples as little as possible. If an item of evidence is perishable it should be frozen.

All items collected should be clearly and accurately marked on the outside of the containers. It is crucial to protect evidence at a crime scene, it is a direct link to a perpetrator at a crime, it is important not to contaminate the evidence. Blood can be used for DNA testing which would provide a direct link to a victim, such as fingerprint preservation. This evidence does not lie, not only can it convict it can exonerate an innocent person.