Detailed Procedure:

To more easily recognize prints at the scene, use oblique illumination (from the side) or soft direct illumination. Even if you cannot see prints with the naked eye, latent prints may be able to be developed by the laboratory. Therefore, consider collecting the item that may bear latent prints. Prints can be recovered from items that are wet, soot covered, and rough textured. If possible, collect the entire object and let the laboratory do the processing for fingerprints. If this is not possible, you may elect to use a processing technique at the scene. Never attempt any procedure that you are not trained and qualified to perform. Consult the laboratory if you have any questions or concerns.

Handle the item as little as possible and try to handle it in areas where fingerprints are less likely to be deposited.

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To collect a porous item that may bear fingerprints:

1. Photograph the item in place.

2. Wear new, unused, clean latex or nitrile gloves. Do not touch the item with bare hands.

3. Make sure the item is dry before packaging. If it is wet, air dry it in still, warm air prior to packaging by placing it on a clean sheet of paper at room temperature, away from direct heat, sunlight, and drafts. Do not package wet items; they may deteriorate.

4. Select an appropriate container, such as an envelope or plastic or paper bag. Label the container with identifying information, including case number, date, exhibit number, a brief description, and your name. Do not use Styrofoam packing materials.

5. Carefully pick up the item, preferably by the corner or areas where fingerprints are less likely to be deposited. Insert the item in the container, and secure the item so it does not shift around or rub against the container during transport. Seal the packaging with evidence tape, and initial and date the tape.

6. Store the item in a secure location, such as a locked evidence van or your vehicle, until you are able to transport it to the laboratory.

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If an item will also be examined for ignitable liquid residue, please consult the laboratory for the proper collection procedure. Items should not be air-dried or packaged in an air-permeable container if they will be examined for ignitable liquid residue.

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If an item will also be examined for ignitable liquid residue, please consult the laboratory for the proper collection procedure. Items should not be air-dried or packaged in an air-permeable container if they will be examined for ignitable liquid residue.

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Laboratory testing of fingerprints on porous surfaces:

Porous items are chemically treated to develop the prints. Prints can then be run through databases for matches and/or compared to known prints.

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Source:

Crime Scene and Evidence Collection Handbook. Bureau of Alcohol, Tobacco, Firearms and Explosives, 2005.