NCJ Number
233763
Journal
Identification Canada Volume: 27 Issue: 3 Dated: September 2004 Pages: 1-48
Date Published
September 2004
Length
48 pages
Annotation
The issue's three featured articles discuss the photography and casting of shoe and tire impressions in snow; describe the Canadian National Field Trials, which compared 1,8-diazafluoren-9-one (DFO), ninhydrin, and the sequence DFO followed by ninhydrin in facilitating the detection of latent fingerprints; and recommend precautions that should be taken to reduce contamination in the collection of DNA samples.
Abstract
The first article notes that although snow can be an excellent medium for recording shoe and tire impressions, snow conditions vary according to whether it is fresh snow, slush, or ice. Each type of snow poses distinctive challenges for the collection and recording of the detail of impressions. Although photographing a white-on-white impression is challenging, the primary skills are the same as those used to photograph other three-dimensional impressions. Snow impressions are sprayed with different coating material in order to increase contrast for photography and to prepare the impressions for casting materials. Casting an impression in snow may be done with either dental stone products or sulfur. The second article describes the Canadian National Field Trials. As a result of these trials, the Royal Canadian Mounted Police (RCMP) will be recommending the sequential use of DFO followed by ninhydrin in detecting latent fingerprints. The DFO and ninhydrin formulations described in this article are recommended as the RCMP national standard. The third article describes the author's experience with particular DNA blood samples that were properly collected and preserved to avoid contamination and decomposition. Upon analysis, however, the samples had degraded to the point that the largest quantity within the sample was 0.43 nanograms. Believing that some substance at the crime scene must have been collected with the samples to cause the contamination, the author recommends swabbing only the surface of a stain in order to avoid collecting any underlying material from the substrate.