I Got This on Tape

There a several methods to reveal latent prints on the sticky side of tape. Why is this important? 1) Tape seems to play an important part in some crimes: abductions, for example. 2) It is difficult to tape something without leaving a fingerprint on the sticky side at some point. 3) It is almost impossible to handle tape with gloves. How do sticky side latents vary from other surfaces? Possibly the contact with adhesive leaves a somewhat different cocktail of fingerprint residues than contact with a smooth surface. I could not find any information on this. I can speculate that skin (epithelial) cells are more likely to left on tape than on other surfaces. Gentian (also called crystal) violet stain has the remarkable property of revealing fingerprints on the sticky side of tape. Gentian violet is a synthetic purple dye with antifungal and antibiotic properties that can be used for cleaning open wounds. In biology, solutions of crystal violet can simultaneously fix and stain certain cells such as bacteria. I am not certain of how gentian violet stains fingerprint residue. It is tempting to propose that it interacts with the DNA of skin cells. It evidently has little attraction to adhesives used in tape manufacturing. It is very easy to use – just dip the tape in an aqueous gentian violet bath for 30 seconds or so then wash off the excess dye under running water. Gentian dye will stain your hands, clothes, etc… so you have to be careful about that. http://www.bvda.com/images/b810_use.jpg

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