Analytical MethodsSelecting a file below will download the file or open it in a new tab where it may be saved as needed.
|Filename / Link||Size|
|Latent Print Examiner Training Manual rev6.pdf||331.75 Kb|
|Latent Prints Methods rev8.pdf||425.94 Kb|
|Latent Prints Quality Manual rev6.pdf||285.91 Kb|
Latent Lift Cards: Latent lift cards need to be filled out completely. At a minimum, the cards should include the date lifted, the name of the person doing the lifting, a diagram of where the latent was removed from the object (an arrow showing directionality is helpful), and the case #. In the event that an identification is made to a suspect, all of this information needs to be present in order for it to be easily admitted into court. If an officer inadvertently lifts their own latent prints, please cross them out. Latent lift cards are evidence. They need to be placed into an evidence envelope, sealed with evidence tape, and have a signature placed across the seal. It is acceptable to package all lifts from the same scene together.
Known Fingerprints: Known fingerprints are also known as ten print cards, palm prints, or major case prints. These are prints taken by officers for the purpose of comparing to unknown latent prints. Known fingerprints may be of the suspect or they may be for victim/elimination purposes. These prints should be dated and signed by both the official taking the prints and the person being printed (if the person being printed refuses to sign, a note should be made to that effect). Known fingerprint cards should be treated as evidence when they are being submitted to the lab. They need to be placed in an evidence envelope, sealed with evidence tape, and have a signature placed across the seal. ISP Forensic Services prefers original copies of known prints for comparison purposes. In the event that originals are not available please submit certified copies.
Photographs of Latent Prints: If you are sending photographs of latent prints, they should be taken with the camera perpendicular (at a 90 degree angle) to the surface being photographed. All photos must include a scale. Digital photos should be shot at as high of a resolution as possible and in TIFF or RAW format if possible.
Tape: It is a good idea to leave the tape on the item on which it was found, and submit the whole item. If however, you need to remove the tape and would like to have it processed for latent prints, try not to fold the tape onto itself. Obtain a piece of heavy gauge plastic (ex. plastic heat seal packaging or plastic page protector – make a note that the plastic is not evidence) onto which you can stick the tape, so the tape can be peeled off to process it. If the plastic is too thin, it may not be possible to peel the tape off without tearing the plastic. *Latent prints may be present on both sides of the tape.
Plastic Baggies: Drugs should be removed from packaging prior to submission. If packaging multiple baggies in the same envelope, layer baggies between sheets of clean white printer paper. If the bags are not separated, latent prints or portions of them, may transfer from one bag to another.
Paraphernalia: In general, items impounded for general evidence collection should be separate from items to be processed for latent prints. It is preferable that only the items that are to be processed be submitted to the lab. If a fabric pouch containing a glass pipe, cotton swabs, and a used tissue is impounded, but only the glass pipe is to be processed, package the pipe in its own envelope for submission or clearly note on the packaging and in pre-log which items need to be processed.
Paper/Cardboard: No special packaging required for this type of evidence. Place in an evidence envelope or bag, seal, sign, and submit to the lab. Paper and cardboard SHOULD NOT be processed using fingerprint powders. Chemical techniques used by the laboratory are much more successful at recovering usable latent prints than powder processing of porous items. In the event that your agency does decide to use black powder processing on paper/cardboard, all latents should be photographed 1:1 at a 90° angle with a scale, preferably in TIF or Raw format. These photographs and negatives should be submitted along with the item.
Guns/Knives: Firearms must be unloaded and the chamber should be secured in an open position before being sent to the lab. Weapons must be secured into a cardboard box with zip ties (the lab often receives weapons that have broken the zip ties –use more than you think you need). Please do not place weapons unsecured in evidence envelopes or boxes as they tend to shift around and the movement within the container may destroy the latent prints. Gun cases with foam inserts are not acceptable packaging. The foam may damage or remove prints from the item. If your agency does decide to submit foam lined gun cases, try placing a layer of butcher paper between the weapon and the foam.
Containers with Liquid: If you have containers with liquid (drink cans or bottles, etc.), dump as much of the liquid out as possible, then manufacture a wick from paper toweling. Place the wick down inside the can to absorb the remainder of the liquid (even a little bit of liquid if left in the container may escape during transport and destroy latent prints). Items known to contain moisture should be packaged in paper bags or evidence envelopes.
*Please take the time to fill out all Victim, Suspect, & Subject information with their date of birth if known, and correct name spelling. If you have a SID# or FBI# for a particular individual, please provide it when filling out the pre-log questions. If available, a copy of the police report should accompany evidence submitted to the Forensic Laboratory for latent print analysis.
**Write on the evidence envelope before putting the evidence inside, so that you are not creating friction or engraving your name and case information on the evidence inside.
*** Paper towels or other tissue papers are not recommended for packaging latent print evidence as:
- it is very fibrous, and the fibers may stick to the evidence,
- it is textured, and the texture has a tendency to rub latent prints off
- latent prints are 99% water, and paper towels are designed to absorb moisture
****Inform the lab during pre-log if the evidence requires other testing such as biology screening, DNA, controlled substance analysis or firearms. It is important that processing proceed in the proper order as some of the chemicals used in the development of fingerprints may be detrimental to other types of evidence.
Please direct additional questions about collection, packaging, or fingerprint casework to the Meridian Laboratory (208) 884-7170.