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Fingerprint Powder Processing

In searching a crime scene, or potential pieces of evidence, the most common item that you search for are latent fingerprints. Being "latent", the prints are, by definition, not readily visible to the naked eye.

As crime scene investigators or evidence technicians you have to process the evidence for "latents" with powders or chemicals. You can develop the latent to the point where you can easily visualize, photograph and/or lift them from the surface for the record.

COMPONENTS:

POWDERS:

There are many types of powders available for processing, such as regular fingerprint powders, magnetic fingerprint powders and fluorescent fingerprint powders.

In selecting a powder it is best to select a powder that is in contrast to the surface on which is being processed.

REGULAR FINGERPRINT POWDERS come in various colors such as black, gray, white, red, dual-use and super black to name a few.

MAGNETIC FINGERPRINT POWDERS come in various colors such as black, gray, white and dual-use to name a few.

FLUORESCENT MAGNETIC FINGERPRINT POWDERS come in various colors such as red and yellow to name a few.

REGULAR POWDERS may be used on any surface, which is relatively smooth and non-tacky. They are not suitable for use on surfaces that are wet, very rough or tacky.

MAGNETIC POWDERS are sometimes more effective on rough, grained or porous surfaces, which would otherwise become heavily coated with regular powder.

FLUORESCENT POWDERS are very strongly fluorescent and can be detected with a low power U-V lamp or an alternate light source such as the Blue Light Special or Blue Light Ultra. This is a very fine powder and is effective on multicolored surfaces, which would otherwise present a contrast problem.


POWDER APPLICATIONS:

FIBER DUSTER is a brush best used with regular fingerprint powders. Use one brush for each color of powder. Do not contaminate the brush by using it in various colors of powder.

FEATHER DUSTER is a brush used primarily with fluorescent fingerprint powders but also works well with regular fingerprint powders. Use one brush for each color of powder. Do not contaminate the brush by using it in various colors of powder.

MAGNETIC APPLICATORS such as the regular pen type, Bubble-Based or the larger Mega-Mag applicator are used with the regular magnetic powders and the magnetic fluorescent powders.


LIFTING/BACKING MATERIALS:

LIFTING TAPES come in various sizes from 1 1/2" to 4" in frosted and clear.

FLAP-LIFTERS come in various sizes and have the clear lifting tape attached to a backing card either white, black or clear.

BACKING CARDS come in various sizes in black or white. Use a color of card to contrast the color of powder being used.


APPLICATION:

PROCESSING STEPS WITH REGULAR FINGERPRINT POWDERS:

1. Photograph any visible fingerprints that you observe.

2. Carefully dip the brush into the appropriate powder. Apply a small amount of powder to the tip of the brush.

3. Apply the powder to the surface with a light twirling motion over the area to be processed. If a heavy deposit appears on a fingerprint, gently brush off the excess powder with a light twirling motion.

4. Photograph any latent fingerprints that have been developed.

5. Apply a short piece of lifting tape. This must be pressed well onto the surface.

6. Slowly remove the lifting tape from the surface and place it on a backing card that is of contrasting color to the powder being used.

7. Properly fill out the back of the backing card with the proper information.

PROCESSING WITH MAGNETIC POWDERS:

1. Place the end of the magnetic applicator that you have chosen to use into the magnetic powder and withdraw, shaking slightly to remove any excess powder. A ball of magnetic powder will have formed, making a "brush-like" appearance at the base.

2. Gently move the ball of magnetic powder over the surface to be processed being careful not to let the head of the applicator touch the surface being processed-this could scratch the latent fingerprint. Continue until you have developed the latent print.

3. Upon completion, hold the magnetic applicator over the powder jar and lift the rod in the center of the applicator to release the powder back into the powder jar.

4. Pass the clean applicator over the area just processed to pick up any excess powder.

5. Photograph any latent fingerprints that have been developed.

6. Apply a short piece of lifting tape. This must be pressed well onto the surface.

7. Slowly remove the lifting tape from the surface and place it on a backing card that is of contrasting color to the powder used.

8. Properly fill out the back of the backing card with the proper information.


PROCESSING WITH FLUORESCENT POWDERS:

1. Photograph any visible fingerprints that you observe.

2. Carefully dip the tip of the feather duster into the appropriate color of fluorescent powder. Apply only a small amount of powder to the tip of the brush. The amount of powder residue in the lid would be adequate.

3. Apply the powder to the surface with a light twirling motion over the area to be processed. If a heavy deposit appears on a fingerprint, gently brush off the excess powder with a light twirling motion.

4. For optimum visibility, use a portable light source or alternate light sources to view the fluorescent fingerprints.

5. Photograph any latent fingerprints that have been developed using a portable light source or alternate light source.

6. Apply a short piece of lifting tape. This must be pressed well onto the surface.

7. Slowly remove the lifting tape from the surface and place it on a black backing card.

8. Properly fill out the back of the backing card with the proper information. (Make sure that you indicate this card contains a fluorescent lift and that you may need a light source for optimum viewing.)



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