Fingerprints
By: Michaela Pelletier
Fingerprints are one of the most important pieces of evidence during a crime investigation. Fingerprints are made up of arches, ridges, loops and whorl formations. There are three types of fingerprints: patent, plastic and latent. Patent fingerprints are the easiest to find because they are visible to the naked eye; these occur when someone has grease, blood, or ink on their fingers and it leaves a print on a surface. Plastic fingerprints are also easy to find but they are not as common as patent fingerprints; these occur when someone touches an object such as soap, wax, or butter and leave a print on a surface. Latent fingerprints are the hardest to find and are the most common type of fingerprint; these occur from the fingers natural oils being left on a surface. It is important to keep in mind that fingerprint evidence is very reliable so the preservation of fingerprints from a crime scene is crucial. The chances of any two individuals having the same fingerprint are about one in sixty four billion.
When lifting a fingerprint, you are making a permanent impression of the fingerprint. You can lift a fingerprint from a flat or round surface. To lift a fingerprint, use a type of tape with an adhesive surface and apply to the fingerprint to leave an imprint on the tape. To ensure the print is lifted properly and completely, a flat object such as a ruler is slowly slid across the tape to get rid of any bumps or bubbles in the tape. Then, the tape is slowly and carefully peeled off the surface and the adhesive side is covered with plastic so nothing can affect the print. Finally, the print should be labeled with identification information and a description of the location on the back of the tape.
Packaging fingerprints is a crucial to a crime scene because the fingerprints must be protected and maintained the correct way. The main fear at all crime scenes is adding or destroying fingerprints that are already present. Gloves should be worn at all times to keep from tampering with existing fingerprints but unnecessary contact should be avoided. It is important to choose packaging of the correct size and material. For fingerprints paper is the best way to package them so they can breathe, they should be attached to an evidence sheet and then put into a 5x7 manila envelope. Every piece of evidence should be packaged separately, sealed, documented, and properly labeled. To mail latent prints the manila envelope should be sandwiched between two sheets of stiff cardboard and wrapped then put into a box.