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Method for Impregnating Nylon Transfer Membranes with Leucocrystal Violet for Enhancing and Lifting Bloody Impressions

NCJ Number
Journal of Forensic Sciences Volume: 49 Issue: 3 Dated: May 2004 Pages: 511-516
Amy L. Michaud; Leanora Brun-Conti
Date Published
May 2004
6 pages
This paper reports on a research project that developed a fast and simple method for impregnating nylon transfer membranes with leucocrystal violet (LVC) in order to lift and enhance impressions made in blood.
The project's first objective was to determine the best formulation of LCV for impregnating the membranes. A literature search found that three primary formulas are being used to compose the liquid form of the LCV enhancement spray. The authors developed a fourth formulation for use in the research. The project's second goal was to ascertain the best method for impregnating the membranes with the LCV solution. Using the four formulations, the LCV solutions were applied to the membranes by spraying or soaking, and then they were allowed to dry. The project also developed a method for remoistening the LCV impregnated membranes for use in the field. A variety of liquids were tested with each of the four formulations to determine which would provide the best results. In order to determine the effectiveness of the prepared membranes, a number of test impressions were made. Using a rubber stamp with fine detail to simulate a fingerprint, impressions were placed on a variety of substrates using varying amounts of blood. The substrates included glass, plastic, paper, cloth, tile, linoleum, metal, untreated wood, carpet, cardboard, and skin. The membranes that were impregnated with each of the four formulations and remoistened using different solvents were then used to lift the prepared impressions to determine which provided the best sensitivity, detail, and contrast. The LCV-impregnated membranes provided excellent enhancement and lifting capabilities on all of the nonporous surfaces tested. None of the impressions were harmed, and in many cases the membranes enhanced and "fixed" the original impression to the substrate even when the membrane itself did not produce a useable impression. LCV-impregnated membranes proved to be more useful for enhancing the impression itself on porous surfaces; however, in some instances the lift provided some useful information regarding class characteristics. In the case of impressions on skin, the quality of many of the lifts provided sufficient detail for comparison. The authors recommend that the impregnated membranes be used within 2-3 months of being made in order to achieve optimum lifting and enhancing capabilities. Enhanced and/or lifted impressions should be photographed shortly after processing. 13 figures, 2 tables, and 4 references