NCJ Number
216802
Journal
Journal of Forensic Sciences Volume: 51 Issue: 6 Dated: November 2006 Pages: 1323-1328
Date Published
November 2006
Length
6 pages
Annotation
Beginning as an attempt to determine what components of a fingerprint residue are important in providing a successful result from superglue fuming, this investigation led to an expanded evaluation of the response of nonpolar compounds (hydrocarbons) to the fuming process.
Abstract
One finding from the experiments was that inorganic salts and amino acids alone would not lead to the desired results from superglue fuming, i.e., the exposure of latent fingerprints that contain these substances. Preliminary experiments with decane and hexadecane (hydrocarbons in fingerprint deposits) responded to superglue fuming, i.e. methyl cyanoacrylate polymer formed at the site of the fingerprint. Films of liquid alkanes responded similarly to actual fingerprints in the fuming experiment. Their responses depended on the hydrocarbon used, viscosity, and film thickness. Aspects such as film thickness apparently are relevant for actual fingerprints as well. A model was developed based on these findings. In this model, gas-phase molecules are exposed to a thin film, some partition into the film. The model is essentially that for column chromatography, such as gas chromatography with two differences. First, this is a static, not a flowing system; second, in gas chromatography (GC), molecules are adsorbed by the stationary phase, diffuse into it, and then diffuse to the surface to reenter the gas phase. Reaction leads to chemical trapping of monomers at the fingerprint film location. All of the considerations useful in the rate theory for GC modeling apply, such as film thickness, volume ratio, and diffusion coefficient considerations. The methods and materials used in the experiments are described in detail, and lessons are drawn for the use of superglue fuming to expose the details of latent fingerprints. 2 tables, 3 figures, and 19 references