Advances in Fingerprint Technology.pdf

3. Expose the tape surface to a high-intensity photo lamp until the latent
prints have developed.
4. Photograph the developed latent prints.
5. With black tape, transfer the developed latent print onto photographic
paper by the following procedure.
a. Place the developed tape between two pieces of RC photographic
paper with the emulsion side of the photographic papers facing the
tape to form a “sandwich.”
b. Place the sandwich between two pieces of 1/8-in.-thick blotter
paper.
c. Heat the blotter paper at low temperature using an iron.
d. Photograph the transferred fingerprint.
Margot and Lennard 9 use a stock solution of 5 g gentian violet and 10 g
phenol (very toxic) in 50 mL ethanol. The working solution is a 1:25 dilution
of stock into water. The processed latents are transferred onto photographic
paper. Other recipes we have seen for the phenol-based reagent use the same
stock solution as Margot and Lennard, but the working solution is a 1:100
dilution of stock into water.
Teuszkowski and Loninga 195 have found that the emulsion side of photographic
paper often sticks to the adhesive side of the tape and suggested
an alternative procedure for processing latent prints on the sticky side of
black tape. Taylor and Mankevich 196 reported using a silver protein staining
procedure to develop latent prints on tape. This method was found to be
very effective when used in conjunction with gentian violet. Hollars, Trozzi,
and Barron described a procedure involving treatment with Ardrox in
detergent solution that was said to work well on dark-colored, sticky surfaces
where gentian violet worked poorly. 197 Bratton and Gregus compared
gentian violet, a commercial “Sticky Side” powder, and a black powder in
detergent suspension on a series of latent prints on various tapes. 198 Prints
in the study were characterized as “initial,” “sebaceous,” and “eccrine.” The
black powder in detergent suspension worked best on the “eccrine” prints,
that are apparently not well developed by gentian violet. Howard 199 used
basic fuchsin processing on black electric tape that does not respond well
to gentian violet; 20 mg basic fuchsin (Aldrich Chemical product was preferred
in limited comparison study) was dissolved in 400 mL methanol or
water, and the test item was immersed for 50 sec to 1 min before drying
and examination under laser light.
Martin 200 reported moderate success in developing latents on smooth
glossy surfaces that had been transferred there from the sticky surfaces of
tapes. Frosted cellophane tape was the most efficient transfer medium.