Latent Prints

Analytical Methods

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For identification purposes, please put the agency name, agency case number, subject name and exhibit number on each evidence package.  Please ensure there is a chain of custody on each evidence package. Pre-log all names known to be associated with the items (subjects, suspects, and victims). Please include birthdates and State Identification Numbers (SID #) if known.

If available, include a copy of the police report when submitting evidence to the Forensic Laboratory for latent print analysis.  The report can be attached during pre-log or submitted with the items of evidence.

 *Paper Toweling/Tissue/Foam is not recommended for packaging latent print evidence.  These items tend to be textured and fibrous.  Friction and texture may damage latent prints.   Latent prints are primarily composed of water and these types of products are designed to absorb moisture.

** Write on the evidence envelope prior to putting the evidence inside. Doing so will allow you to avoid engraving case information on the evidence.

***Note if the evidence requires other testing such as Controlled Substance, Firearms, or DNA on the packaging and in pre-log.  Scientists from each unit will work together to ensure processing and collection proceed in the proper sequence.

Latent Lift Cards: latent lift cards need to be filled out completely.  Lift cards should include the date lifted, the name of the person who lifted it, a diagram of where the latent was lifted from the item (an arrow showing directionality is helpful), and the case #.  This information needs to be present for admission into court.  It is highly recommended that officers performing powder processing wear gloves.  If an officer inadvertently lifts their own latent prints, please cross them out.  Latent lift cards must be submitted as evidence. Latent lift cards from the same scene can be packaged together.  The item that the latent prints were lifted from does not need to be submitted to the laboratory.

Known Exemplars: also known as ten print cards, palm prints, or major case prints, are prints taken by officers for the purpose of comparing to unknown latent prints.  Known exemplars may be of the suspect or they may be for victim/elimination purposes.  If a person involved in your case has an FBI # or SID# (State Identification Number) please provide that information during pre-log.  This will allow forensic service staff to access cards for comparison.

If your agency is taking and submitting known exemplars, they should be dated and signed by both the official taking the prints and the person being printed (document if the person being printed refuses to sign).  Known exemplars must be packaged and submitted to the lab as evidence.  ISP Forensic Services prefers original copies of known prints for comparison purposes- these will be returned to you.  In the event that originals are not available, submit certified copies.

Photographs of Latent Prints:  if you are submitting 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 RAW or TIFF format if possible.  These formats are available on cameras with removable lenses but some fixed lens and cell phone cameras may also have this capability, check your settings before photographing.  Please note that lower resolution photos and photos that are captured in other formats may not be able to be used for comparison purposes. If you have digital photographs for comparison, copy them to a DVD or USB drive and submit as evidence. The item that the latent prints were photographed from does not need to be submitted to the laboratory.

Tape to be processed for Latent Prints: generally, it is a good idea to leave the tape on the item on which it was found, and submit the whole item.  If you need to remove the tape and would like to have the tape processed for latent prints, avoid folding the tape onto itself.  Adhere the tape to a piece of heavy gauge plastic (heat sealed packaging or plastic page protectors) so that it can be peeled off for processing.  If the plastic is too thin (baggies/plastic wrap), the lab may not be able to remove the tape off without tearing the plastic. Please note, latent prints may be on the adhesive side of the tape as well as the non-adhesive side.

Plastic Baggies: controlled substances should be removed prior to submission.  It is alright to place multiple bags in the same evidence envelope as long as they are separated by sheets of smooth, clean, paper.  Latent prints or portions of them, may transfer from one bag to another if the bags are not separated.

Paraphernalia: items impounded for general evidence collection should be separated from items that need latent print processing.  Only the items that require processing should be submitted to the lab.  If a fabric pouch containing a glass pipe, cotton swabs, and a used tissue is collected, but only the glass pipe is to be processed, package the pipe in its own envelope for submission to the lab.  Only submitting the items that require processing will decrease turnaround times.

 Paper/Cardboard: package as evidence 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.  Any prints that your agency develops on paper or cardboard should be photographed.

Guns/Knives: firearms must be unloaded and the chamber secured in an open position before being sent to the lab.  Avoid inserting zip ties or other items through the barrel.  Weapons must be secured to a cardboard box with zip ties.  Use multiple zip ties as items tend to shift around and the movement within the container may cause items to tear loose and damage latent prints.  Gun cases with foam inserts are not recommended for packaging. If you must use a foam lined gun case, place a layer of butcher paper between the weapon and the foam. If your agency utilizes trigger locks, please note that your agency placed the lock on the firearm and that it does not need to be processed.

 Containers with liquid: if you have containers with liquid (drink cans, bottles, etc.), remove as much of the liquid as possible, then manufacture a wick from paper toweling.   Place the wick down inside the can to absorb the remainder of the liquid and remove wick prior to packaging if possible.  Even a little bit of liquid if left in the container may escape during transport and damage latent prints.  Items known to contain moisture should be packaged in paper bags or evidence envelopes.

Prints in Blood: should be photographed and the item collected for submission to the laboratory. The laboratory has chemical techniques available for the enhancement of blood.  Attempting to lift prints in blood is not recommended.

If you have any questions about collection, packaging, or casework, please call the Meridian Lab (208) 884-7170 and request to speak with a scientist in the latent print unit.

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