The tickle of curiosity. The gasp of discovery. Fingers running across the keyboard.

The tickle of curiosity. The gasp of discovery. Fingers running across a keyboard

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Tuesday, March 19, 2013

Footwear Evidence for Writers – by Patti Phillips

Conferences are a blast for the mystery/thriller writing crowd these days. And not just because of the workshops improving our craft and technique providd by the many writing organizations. I appreciate those I do. But for all-out, slam-dunk fun, I go to the Writers' Police Academy (founded by Lee Lofland). It’s a three day, hands-on, mind-blowing experience that demonstrates the nuts and bolts of police and fire and EMS procedure – taught by professionals and experts actively working in the field. All with the purpose of getting writers to improve their technical knowledge so that they can get it right on the page.
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Along with several other strands of study, the last two WPA conferences provided classes in bloodstain patterns, fingerprinting, and alternate light sources (ALS) conducted by Sirchie instructors. Because of the standing room only enthusiasm for these classes, Sirchie offered a five-day Evidence Collection training session for writers at their own complex in North Carolina. Sirchie makes hundreds of products for the law enforcement community and I felt this would be a great opportunity for Detective Kerrian (my protagonist) to learn more about the latest and best gadgets being used to catch the crooks.


Wolverine cast

Criminals rob, murder, rape or otherwise inflict bodily harm upon their victims. Physical evidence at a crime scene is an essential part of figuring out what happened. It is up to the police officers, investigators, and examiners to recognize what is and is not part of the evidence and then interpret the importance of each fiber, fingerprint, bloodstain, and other material in order to secure a conviction of the correct individual.

One of the most overlooked pieces of evidence at a crime scene is created by footwear.

If a window breaks as a thief enters the premises during the commission of a burglary, the glass will fall into the house, and onto the floor or rug below the window. When the thief steps through the window, unless the thief has wings, he/she will probably plant a foot right in the middle of the glass. And walk through the house, most likely tracking minute pieces of that glass. That glass may also become embedded in the grooves of the sole of the shoe, creating a distinctive footprint.

If the investigating officer can place a suspect at the scene with the footprint, then there is probable cause to fingerprint that suspect and hopefully establish a link to the crime.

A new method of eliminating suspects right at the scene involves stepping into a tray that contains a pad impregnated with a harmless clear ink that doesn’t stain, then stepping onto a chemically treated impression card. (So safe that it’s often used on newborn babies for the hospital records) No messy cleanup, immediate results, and it can even show details of wear and tear on the shoe. This can be a way to establish a known standard (we know where this impression came from) to compare with multiple tread prints at the scene.



Footwear Clear Ink Impression

Another tool for creating a known standard is the foam impression system. It takes a bit longer, (24 hours) but clear, crisp impressions can be made, including of the pebbles and bits stuck deep into the grooves and the writing on the arch. Very helpful when trying to place suspects at the scene. A rock stuck in the sole is a random characteristic that can’t be duplicated, so becomes another point of identification.

We definitely wanted to try this method for ourselves. Each of the writers stepped into the box of stiff-ish foam – a bit like stepping into wet sand.



Using foam impression system

An impression is made instantaneously. Look at the detail – down to the wear on the heel.



Foam impression of Wolverine boot

We used pre-mixed dental stone (made with distilled water and the powder) to fill the impression.



 Making the cast with pre-mixed dental stone

We waited 24 hours for them to become firm enough to pop out of the foam. We now had permanent records of the footwear treads, which could be used for comparison to other prints found at the scene. There were more than a dozen of us walking through that room every day on a regular basis and assorted other visitors tramping through the perimeter. If a crime occurred before we left for the week, we’d have a LOT of eliminating to do, but we were ready!


Photo: Footwear casts


Occasionally footprints are found on the ground outside a window or in the gardens surrounding a house after a burglary or homicide. Ever see a crime show on TV  where the fictional investigator makes a snap judgment about the height and weight of the owner of the footprint because of the depth of the impression? That’s merely a plot device and is not scientific evidence in real life. A crime scene photographer or investigator can photograph the footprint (next to a measurement scale), make a take away cast, and then compare the impression with those of the suspects or other bystanders at the scene. Beware: making a cast of the print destroys the print, so a photograph must be taken before pouring that first drop of dental stone.

Footprints can be found at bloody crime scenes as well. The suspect walks through the blood, tracks it through the house, cleans it up, but the prints are still there, even though not obvious to the naked eye. As we learned during the ‘Blood and Other Bodily Fluids’ session, blood just doesn’t go away, no matter how hard you try to get rid of it. It seeps into the cracks and crevices of a floor and even behind baseboards.

A savvy investigator will collect sections of carpet (or flooring) taken from where the suspect might have walked during the commission of the crime, then conduct a presumptive test for blood (LCV - Aqueous Leuco Crystal Violet), find a usable footprint, compare it to a known standard, and then be able to place the suspect at the scene.


Footwear Print

Kudos to Robert Skiff, the Sirchie Training Manager/Technical Training Specialist who conducted the classes with his assistant, Chrissy Hunter, all week. He fielded our many (sometimes wild) questions with solid expertise as we attempted to find the perfect scenarios for our fictional crime-fighters and criminals.

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Patti Phillips is a transplanted metropolitan New Yorker/north Texan, now living in the piney state of North Carolina. Her best investigative days are spent writing, cooking, traveling for research, and playing golf. Her time on the golf course has been murderously valuable while creating the perfect alibi for the chief villain in “One Sweet Motion.”

Did you know that there are spots on the golf course that can’t be accessed by listening devices? Of course, it helps to avoid suspicion if you work on lowering your handicap while plotting the dirty deeds.

Patti Phillips writes the www.kerriansnotebook.com blog and the book review site www.nightstandbookreviews.com

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1 comment:

  1. Hi - I am wondering if I could use the image of all of the casts of footwear in a book I'm writing. Do you own the image, or do you know who does? My book is about casting in all materials and my co-author and I would love to have at least one image of the forensic angle to casting. Please send me an email regarding this image if possible.

    Thank you so much!
    Jen Townsend
    cast.jen.and.renee@gmail.com

    ReplyDelete