Getting The Most Of Your Fingerprint Powders

Kevin M. Parisi
Fingerprint Technician
New Hampshire State Police Forensic Laboratory
10 Hazen Drive
Concord, NH 03305

Reprinted from the Summer, 1998 issue of New England Division Journal

The development of latent (fingerprint) impressions on adhesive surfaces is a relatively new technique, as noted in the 1994 article in the Journal of Forensic Identification entitled “Sticky Side Powder,” as well as a 1997 article in Fingerprint Whorld entitled “Development of a Black Powder Method to Process Adhesive Tapes.” Both methods are easy to perform, and achieve extraordinary results. Realizing a common element in the two techniques, I obtained and tested additional powders using photo-flo and liqui-nox detergent on selective surfaces. The powders used were Lightning Powder Pink-Wop Fluorescent Powder and SirchieWhite Fingerprint Powder.

Tape surfaces

Grey duct tape
3M Scotch tape 2″ wide clear plastic tape
3M Scotch Magic tape ¾” X 1296 clear plastic tape
Black electrical tape

Method 1

.5 grams Lightning Pink-Wop
3 ml Liqui-nox detergent
3 ml distilled water

Method 2

.5 grams Lightning Pink-Wop
3 ml Kodak photo-flo

Method 3

.5 grams Sirchie white fingerprint powder
3 ml Liqui-nox detergent
3 ml distilled water

Test A

Mix contents of method 1 and method 2 in separate 50ml glass beakers, using a camel hair brush until the solutions reach a consistency of lather (similar to shave cream.) With the brushes used for mixing, apply solutions of the two methods to the adhesive surface of the selected tapes (having placed known fingerprints on the surface prior to the test.) Rinse the tape under cold slow running tap water to remove excess powder. The processed tapes should then be examined under an alternate light source, (530 nm).

Results

Method 1 produced excellent results, developing identifiable prints on each of the selected surfaces. The contrast of the latents improved with additional applications of the solution. Method 2 failed to produce positive results.

Test B

Tape used s in test A were first treated with exposure to cyanoacrylate (superglue) fumes for eight minutes, and then were treated with method 1 and method 2. Each were rinsed under cold tap water which removed excess powders. Subsequently, the tape was then examined under the alternate light source, again at 530 nm.

Results

Although the developed latents appeared “segmented” method 1 produced identifiable prints. The segmented area was due to the glue fumes. Method 2 failed to produce identifiable prints.

Test C

Solution 3 was mixed then applied in the same manner as methods 1 and 2, to the adhesive side of the black electrical tape. Excess was also removed with cold running tap water.

Results

This method produced extraordinary results with the development of identifiable fingerprints. The prints increased with additional applications.

Conclusion

The development of fingerprints on adhesive surfaces can be achieved by utilizing a variety of powders. Improving the contrast can be enhanced by increasing the number of applications. Examiners can also approach the processing of adhesive surfaces in the same manner as when using conventional powders to process non-porous surfaces. For example, using method 1 when processing light/white colored surfaces, andmethod 3 when processing darker surfaces.