Law Enforcement Technology

NOV 2014

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INVESTIGATIONS 26 Law Enforcement Technology November 2014 www.officer.com One complication officers encoun- ter is the lack of contrast. To mitigate this, shadows can be created. "You can spray paint the shadow of the impres- sion," says Wolfe. "We coat the entire impression with gray primer and then use the oblique light source to bring up the details of that impression. You're coating all the crystals so you see the surface of the snow." After photographing impressions a cast can be made. Casting is impor- tant due to the difficulty in getting an accurate shot and the inability of pho- tographs to capture three dimensional details. "If there is a cast, then that size is the actual size of the impression," explains Hammer. Casting in snow, again, has unique complications. "The problem with casting in snow is you have to have a casting material that can set and hold its shape before the snow melts," says Wolfe. "The second big thing is the snow grain. You need to make sure that your material is not going to seep through like a snow cone." Three main casting materials, two that have been around a long time and one that's rela- tively new, can be used: dental stone, sulfur cement and snow stone. Dental stone One of the two casting methods utilizes gypsum-based products, including den- tal stone which has been in use the lon- gest. "Dental stone is more common," explains Wolfe. "It's cheap and most agencies have it because that's what you use for casting mud and dirt tracks." Wolfe explains the process of using an accelerator to speed up the setting: "Prior to mixing, we cool the whole thing. We try to get the dental stone down below freezing. We add snow to the water. The idea is the mixture is below freezing so it won't immediately melt the snow." Because the consis- tency of snow can sometimes create the problem of dental stone running right through, many investigators use a layer of snow print wax to coat the Source Code: EBR ENDLESS POSSIBILITIES Everything you need to maintain, repair, customize and shoot your guns All products 100% GUARANTEED – FOREVER brownells.com 800-741-0015 A S H O O T I N G H E R I T A G E A S H O O T I N G H E R I T A G E E S T . 1 9 3 9 E S T . 1 9 3 9 Circle 44 on Reader Service Card Multi-colored paint makes marking tracks and evidence easy to locate, even at night. Snow is a great medium because it is nearly impossible not to leave a track.

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