CSI Footwear Impressions

Week 10

Types of Evidence:

Impression Evidence

Types of Impressions

  • Footwear

  • Tires

  • Toolmarks

  • Bitemarks

  • Fabrics

Comparison Exam

Compression mark: Pushed into a material capable of picking up an impression.

Sketches of crime scene, then of prints

What to write; how you:

  • lifted

  • photographed

  • processed

the footwear impressions

Take overall, then closeups of sections

How did you figure out it was a footwear/sneaker impression—use geometrical shapes to describe directionality

the curvature of the toes are pointed up/down

Arch determines left/right

ACE-V

Analysis Comparison Evaluation - Verification

Manufacturing differences are significant because it can bring you back to the model

The one found at the crime scene and how you describe it is the measurable.

You don’t really need scientific terms

“Voids” on the pattern, “recessed areas” in the footwear itself

You are inverting it to photograph it (the sneaker)

  • Copy regular photo

    • And relabel that it was flipped

Ligature marks

mm in diameters

where the body was found

What do I as the CSI need = critical thinking

Inside of the sneaker

No directionality = just a transfer pattern

You don’t have to say what it is, but if it looks like a comb say it looks like a comb.

Swab for DNA

FLASH USE THE FLASH

Equipment you used

Teeth is the mechanism of a pattern analysis:

Distortion

Shoe sole or tire tread condition

Contaminants: quantity and quality

Receiving surface type and condition

Moisture

Movement and distortion

Degradation of impression before recovery

Weather: temperature, rain, snow, wind

What the Examiner Needs

Examiner has to have the shoe (photograph)

CLASS: Make, model, common manufacturing characteristics, + GENERAL WEAR

            (right away)

INDIVIDUAL: Random nature and microscopic imperfections found on tools are a result of

their manufacture and usage. Can include unique manufacturing errors or mistakes

Photograph it with these details.

Unknown/questioned item of evidence

Known footwear/tire source (not just photos)

Need to know date footwear/tires obtained vs.

date of crime

This may account for changes in tread wear

Elimination prints & photos of first responders

or victim’s/witness’s footwear/tire tread