impressions asistm project forensic investigations
TRANSCRIPT
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.
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.
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.