FSC239Y5 Chapter 17: Chapter 17 (other impressions).docx
Document Summary
Evidence may be in the form of a shoe, tire, or fabric impression. Photography is an important first step in preserving an impression. Lifting impressions when impression on a surface that cannot be taken to the laboratory. Lifting and preserving dust impressions involves use of portable electrostatic lifting device. Impressions can be transferred to mylar film through attraction of charges. Dust impressions can be enhanced by chemical development. When shoe and tire marks are impressed into soft earth at crime scene, their preservation is best accomplished by photography and casting. Class 1 dental stone, a form of gypsum, is recommended for making casts of shoe and tire impressions. Cast should be left to air dry for 24-48 hours before it s shipped to the forensic lab. An aerosol product called snow impression wax is available for casting snow impressions. An automated shoe print identification system developed in england, called shoeprint image.
