Efforts to improve latent fingerprint impression processing using fluorescent and colored superglues
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The use of cyanoacrylate (CA) as a fuming technique for the development of latent friction ridge skin impressions has been widespread for decades within the forensic lab as well as in the field at crime scenes. Important features of processing latent print impressions using this method include that it makes visible latent print impressions that for the most part cannot be seen with the unaided eye and it preserves latent print impressions for future processing/examination. The superglue fumes "fix" the latent print impression to the substrate making it difficult to wipe away, thereby decreasing the chances of destruction during packaging at the scene, transportation, and processing in the lab. One of the disadvantages to this technique is the lack of contrast between the white polymers that are formed on the latent print impression residue and light colored backgrounds on which the latent print impression may be present. Attempts were made to develop a one-step cyanoacrylate fuming method that would enhance visualization of latent print impressions on light colored backgrounds without the need for an alternative light source, dye staining, or powdering. Latent print impressions were applied to black and white ceramic tiles, white painted wood and white/translucent textured plastic. Protein and hemoglobin stains, commercial colorants, sublimation dyes, hair dye, and printer ink were added to ethyl-CA in an attempt to create a co-polymerization process of the vaporized cyanoacrylate monomers and colorant molecules on latent print residue. Fuming was also attempted using pre-colored commercial glues with the assumption that the attached CA polymers on the latent print impression residue would retain their original color properties. None of these methods proved successful. The practical use of a new fluorescent CA, Lumicyano^TM, was also examined. Following fuming, an ALS is utilized for the excitation of the developed latent print impressions using this technique. Strong fluorescence could not be observed on all substrates. In this particular study, fuming with traditional CA followed by the application of powder or dye stains to latent print impressions currently appears to be the most efficient technique for latent print enhancement on the white or light colored substrates used in this study.