The accelerated polyvinyl-alcohol method for GSR collection - PVAL 2.0

The polyvinyl-alcohol collection method (PVAL) is used in forensic practice to gather topographical information about gunshot residues (GSR) from the hands to decide if the subject has made use of firearms. The results allow a distinction between suicide and homicide. The only inconvenience of PVAL was that the procedure took about 60 min because three layers of liquid PVA L had to be applied and dried. Therefore, the collection method was only ap plied to corpses. The improved and accelerated PVAL 2.0 uses a sandwich tec hnique. Cotton gauze for stabilization is moistened with a 10% PVAL solutio n. A solid film of PVAL (Solublon(R)) is spread on the cotton mesh. The gau ze is then modeled to the hand and dried with a hair dryer. After removing the cotton gauze, the traces are embedded in the water-soluble PVAL. The pr ocedure does not take more than 15 min. The results demonstrate the qualiti es and advantages of PVAL: topographical distribution of GSR, highest gain of GSR, sampling of all other traces Like blood, backspatter etc., and humi dity does not reduce the gain. In addition, with the new PVAL 2.0 dislocati on of GSR or contamination are excluded. PVAL 2.0 can also be applied on li ve suspects.