Class Notes: CSI Muskego

Evidence gathering uses a little old detective work with new technologies to tell a story and capture suspects.

We've gotten to the middle of our coursework, and the fifth session of the Muskego Police Citizens Academy had students donning their proverbial Sherlock Holmes hats to see what is left behind at the scene of a crime.

Police have hundreds of options to find clues and evidence, carried in large tackle boxes and containing various tools and powders - this is the apothecary of police science.  Officer Gary Mrotek explained that he loves the investigation part of his job, and has an obvious passion for piecing together what happened where and by whom.

Key to telling any story is in the pictures, and with much less expensive digital technology allows for an unlimited amount that can be taken at a scene of a crime or an accident. However as Mrotek explained, photos should always include scale to pinpoint distance between objects, as the place they receive the most scrutinity is in court, and defense attorneys can cast doubt on a case without it.

For example, he said he always places a cone at an accident scene prior to taking photos from multiple angles to give a point of reference when reviewed later. He also said tape measures are placed relative to objects in a room, and can prove whether a suspect is lying in his testimony or not.

Our class was given two tasks that had to be completed successfully before we could leave.  The first was to match fingerprints found on a soda can with a 'line up' of prints to determine a match.

As many know, fingerprints are like snowflakes - no two people ever have had the same.  Attempts to erase through chemical means really has only made them more unique, Mrotek explained.

Fun fact: Super Glue contains methyl cyanoacrylate, and the fumes literally adhere to the oils in a print to set them and make them even more visible. Our prints that we needed to lift were already exposed to these fumes and helped us 'rookies' in finding them. 

A ferrous talc is then applied, and as its name suggests, it's an iron powder that is gathered on a magnetic wand, lightly brushed over the print to make it darker and easier to read once lifted using a special tape and set on a white background.

I was happy to find my match pretty quickly, as everyone else in our class did as well. 

Task two was tool mark impressions.  Burglars always need some type of tool to get in through a window, although Mrotek said most burglars gain entry with a swift kick to the front door of the house. Dead bolts aren't effective if the door frame is basically three-quarter-inch pine.

Each of us had a block of wood, marked with the impression of a tool.  A mixture of pastes that sets within minutes (basically the same material that dentists use to get teeth impressions) is applied onto the impression and peeled once ready.  Again, our task was to match the mark with a tool from an assortment in Mrotek's toolbox.

Your eye is quickly trained to find that oddity in the impression, similar to an unusual scarring on a fingerprint that distinguishes it from others.  My impressions had a shallow bevel to them, with a burr on one end that helped me narrow it down to a hexagonal lug wrench.

Mrotek also demonstrated the use of light sources to find sweat, blood and other bodily fluids that flouresce or glow in certain light. 

Where suspects tread, options are also varied, from taking photographs if prints are clear, or using a special film that is electrostatically charged to pick up dust particles to capture a print.

Overall, the class made it clear that many times the most effective weapons in a police officer's ability to catch a thief are keen senses and a well-stocked evidence kit.


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