Impressions ASISTM Project Forensic Investigations.

Impressions

ASISTM ProjectForensic Investigations

Shoeprints

The physical contact between the shoe and the surface results in a transfer of the individual characteristics of the shoe.

Shoes prints are often used to prove that suspect was present at a crime scene.

3-dimensional impressions

Footwear impressions are pressed into a soft surfacesuch as mud.

The impression is influenced by the weight of the person and the type of surface.

Casting a 3-dimensional impression

Photography Paul Ricketts, 2006

Sports Shoes

Photography Paul Ricketts, 2006

Boots

Photography Paul Ricketts, 2006

Lady’s shoes

Photography Paul Ricketts, 2006

Using Alginate to make an impression

1 - alginate powder

2 - pour the alginate into a plastic bag 3 - about 1/3 of a bag

Photography Paul Ricketts, 2006

4- add water 5 - squish the powder and water

6 - thoroughly mix7 - cut a small hole at a corner of the bag with scissors

Photography Paul Ricketts, 2006

8 - squeeze out the alginate onto the impression. Work quickly as alginate dries very fast.

9 - carefully pat into place

10 - the alginate changes colour when dry - carefully lift from the impression

Photography Paul Ricketts, 2006

10 - wash away as much dirt as possible

The finished impression

Pict of finished impression - to do

Photography Paul Ricketts, 2006

2-dimensional impressions

2-dimensional impressions occur when an image of the print is left on the surface.

Some 2-dimensional impressions are highly visible – muddy footprints on a cleaned floor – while others are latent or invisible.

2-dimensional impression: Blood

Photography Paul Ricketts, 2006

Photography Paul Ricketts, 2006

Latent 2-dimensional impression: luminol

Other impressions

Casts can be taken of the impressions ofother objects. Eg, tyre tread

Tyre tread

Photography Paul Ricketts, 2006

Tyre tread on ground

Photography Paul Ricketts, 2006

References

Images• All photography by Paul Ricketts, DUIT Multimedia, the University

of Western Australia.• J. Baines is the model for the sequence of photographs showing

taking a shoeprint impression using Alginate.• Shoes supplied by J. Dook.• Graphic design of slides by Trevor Hutchison, DUIT Multimedia,

the University of Western Australia.