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Abstract: The rutile forms of titanium dioxide work very well for developing latent prints on dark surfaces. When used as a substitute for Sticky-side powder, they produce excellent results on black electrical tape and have the added advantage of developing prints on both sides of the tape. They also work well on plastic bags and cellophane. Titanium dioxide powder can be used as a white fingerprint powder or may be mixed with water and Kodak Photo-Flo to make a white small particle reagent.
Background and Procedures
The development of latent prints on some dark surfaces has often posed a problem because most processes produce dark colored prints, rendering them difficult to see. A previous effort to visualize prints on dark tape required the use of a fluorescent reagent [1]. Titanium dioxide (TiO^sub 2^) is a chemical that, for the most part, has been overlooked for its value in developing latents. It is a very fine, nontoxic, nonflammable, white powder with particles much smaller than a micron in diameter. When used to develop fingerprints, it contrasts very well with dark surfaces.
In August 2001, I attended the FBI's Administrative Advanced Latent Fingerprint School in Quantico, Va. One of the requirements of this course was to write a research paper on a fingerprint related topic. The topic I chose was "Development of Latent Prints on Adhesive Material". I had heard of small particle reagent (SPR) being used in lieu of Sticky-side powder on black electrical tape because it had better contrast with the dark surface; however, SPR is also dark in color. I began to experiment with some of Sirchie's Small Particle Reagent-White (SPR-W) in the FBI Academy's laboratory. SPR-W is simply TiO^sub 2^ particles in a mixture of Tergitol and water.
SPR-W was used to process a piece of black electrical tape, with prints applied to both the adhesive side and the nonadhesive side. The results were not impressive. Prints were faintly visible, and the tape basically turned gray.
It was suggested that some Kodak Photo-Flo be added to the SPR-W to see whether that would produce a better result [2]. A mixture of 2 parts SPR-W to 1 part Kodak Photo-Flo (PF) was then made. Another piece of black electrical tape was processed...