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How To Take Latent Fingerprints

     Latent prints are those that cannot be seen by the naked eye. They are caused by the perspiration and other materials that may be on the ridges of the skin. The method used for obtaining latent prints depends on the type of surface to be examined, the manner in which the prints were left, and the quantity of material taken to the crime lab. They are compared to the prints of all persons known to have been at the scene of the crime or who had legal access to the crime scene. This procedure eliminates all but the criminal's prints. Making such prints visible is a matter of both skill and luck. The folowing steps provide instructions on how to take latent fingerprints.


1. Dust the surface with the appropriate powder and lightly dust the area containing the print. (You can choose the appropriate powder by using a powder that will contrast with the surface of the print.)
2. After the print is developed, remove the excess powder by gently blowing or brushing it away. Be careful not to destroy the print with too hard a brush stroke. The "trick" is to use a small amount of powder, gentle strokes, and brush along the direction of the ridges. You might want to use oblique lighting to help visualize the print before you begin. 
3. Use caution to clear away the excess powder around the print before you lift it. 
4. To lift the print from the dusted item to the index card, obtain a 3"-4" length of and place one end of tape to the right of the print and allow the tape to cover the whole print. Be sure that the tape is flat and has no air bubbles. 
5. Slide a finger over the tape and smooth it down over the print to force out all air bubbles. 
6. The print can be removed pulling up on one end of the tape and then placing it on the fingerprint card in the same manner as the tape was placed over the latent print. 


MAGNA BRUSH is a specially designed magnet, which picks up finely divided metallic powder. The brush has no bristles, so only the powder touches the surface containing the latent print. This characteristic reduces the chance of destroying or damaging the ridge detail of the print, which can happen with a bristle brush. This method also permits the use of the same powder over and over again, conserving the powder and leaving cleaner surfaces. Excellent latent prints have been developed on paper, wood, leather, and other slightly porous surfaces using the Magna Brush Follow teacher demonstration of this instrument.