Csm15 July 03 Tyre Presentation Number Three July 2003 TYRE SAFETY TYRE DAMAGE and FAULTS.
Shoe and tyre impressions
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Footprints Footprints give Footprints give information about: information about: The number of criminals The number of criminals Points of entry and exit Points of entry and exit Position of the suspects Position of the suspects Direction of movement Direction of movement through the crime scene. through the crime scene. Time period (eg short- Time period (eg short- lived impressions in lived impressions in frost, snow and dew) frost, snow and dew) Sequence and manner Sequence and manner (walking, running, (walking, running, limping, staggering). limping, staggering). The type, size and areas The type, size and areas of wear on the shoes. of wear on the shoes.
description
Forensic Science Shoe and Tyre Prints Year 10
Transcript of Shoe and tyre impressions
FootprintsFootprints give information Footprints give information
about:about: The number of criminals The number of criminals Points of entry and exitPoints of entry and exit Position of the suspectsPosition of the suspects Direction of movement Direction of movement
through the crime scene.through the crime scene. Time period (eg short-lived Time period (eg short-lived
impressions in frost, snow impressions in frost, snow and dew)and dew)
Sequence and manner Sequence and manner (walking, running, limping, (walking, running, limping, staggering).staggering).
The type, size and areas of The type, size and areas of wear on the shoes.wear on the shoes.
Manufacturer, model and size: - general outsole patterns, shapes, features and markings can help examiners identify the manufacturer, model and size of the footwear. Can be used to profile the suspect and provide leads on who may have bought or worn the footwear.
Approximate height: Investigators refer to statistical data to approximate the height of the person. Height can also be approximated by stride length.
Footprints
Footprints
• Activity of wearer: The footwear imprint left by a person is different when they are walking, running or carrying something. An impression left by a running person will be deeper in the heel and toe sections of the shoeprint. A person carrying a heavy load will cause deeper prints.
• Link between a print and a piece of footwear: Every piece of footwear will show different amounts of tread wear and damage (tiny cuts and nicks).
Footprint impressions When someone walks
over soil, impressions are left in the ground.
To collect the evidence a frame is built around the print and suitable casting material poured in (usually plaster of Paris) and allowed to dry.
The cast is then removed and photographed.
Other ImpressionsOther Impressions2-dimensional impressions occur when an image of 2-dimensional impressions occur when an image of
the the print is left on the surface. print is left on the surface.
Some 2-dimensional impressions are highly visible – Some 2-dimensional impressions are highly visible – muddy footprints on a cleaned floor – while others muddy footprints on a cleaned floor – while others are latent or invisible. are latent or invisible.
Footprints in blood Developed using Luminol
Tyre ImpressionsTyre Impressions
Casts can be taken of the impressions Casts can be taken of the impressions ofof
other objects. Eg, tyre treadother objects. Eg, tyre tread
TaskTask- Casting a Footprint• Gently stand in the sandpit to make an impression• Place a ruler against the footprint and take a
measurement• Photograph the footprint• Frame the footprint with four pieces of card or an
plastic frame• Apply fixant (hairspray) to help preserve detail.
(optional)• Mix up the plaster and pour into the footprint
impression.• Leave to harden and then remove cast and wash excess
sand off the cast.• When hardened footprint is analysed for nicks, cuts and
worn patterns are noted
