Forensic analysis of Footwear Impression Evidence pptx.

formation of footwear impressions, gait characteristics, 3D and 2D casting of Footwear impressions

1. Footwear Impression Evidence Presented By Priyanka Gadisetty

2. Impression Evidence Defined as – “objects of materials that have retained the characteristics of other objects or materials through direct physical contact” Fingerprints, palm prints, footwear impression, tire impressions, bite marks, glove prints, footprints, socked foot impressions, firing pin impressions, lip impressions, ear impressions Plant and animal fossils

3. Footwear impressions Found en route to, at, and exiting from the crime scene Link between the criminal and the place where the crime occurred Found in very small percentage of cases Difficult or inconvenient to find Ground surfaces Latent prints Requirement of specialized lighting techniques Little of no experience of investigator Rush in searching crime scene Limited knowledge of footwear impression examination

4. Footwear impressions Frequency of footwear impressions Durability of footwear impression Age of impressions Positive identification of footwear

5. Information Provided Type, make, description, and approximate or precise size of the footwear that made them Process of developing a suspect Crime reconstruction Determining the number of suspects, their path into and through the crime scene, their involvement in the crime, and the events that occurred during the crime Corroborate or refute the information provided by witnesses or suspects

6. Gait Characteristics

7. Formation of footwear impressions Creation of static charges – clean, dry shoes, taking several steps and then walking across and stepping on a hard flat surface such as a tile floor Deformation of the surface – soil, carpets, etc. – use of holography Transfer of a trace or residue materials – negative and positive images

8. Areas to check Actual point of occurrence of the crime Point of entry Path through the crime area Point of exit and other exterior areas Near other footwear impressions

9. Handling footwear impressions Take general crime scene photographs – take examination quality photographs Make notes and crime scene sketches Remove the impressioned item from the scene Never cover an impression with tape or plastic

10. Casting 3D footwear impressions Significant depth in addition to length and width Superior to photography Photography and casts must be used to supplement each other Possible loss of details in photographs Casting materials – silicones, moulage, paraffin wax, alginates, plaster of paris , and dental stones Silicones – Expensive, too thick to flow in impression, take longer time to cure Paraffin wax – 20 – 30 min to melt, more quantity is required

11. Qualities for a good casting material

12. 2D footwear impressions Electrostatic lifting: It is a tool that electrostatically charges particles within dust or light soil, which are then attracted and bonded to a lifting film. This method is best for collecting dry or dusty residue impressions on almost any surface, even the skin of a cadaver. Imprints and impressions may be further processed to enhance or bring out additional minute details. For example, a digital enhancement program such as Adobe Photoshop® can be used to improve the quality of a photographed impression. Fingerprint powders and chemical stains or dyes can enhance image color or increase the contrast against the background. This enables lifted or casted evidence to be photographed or scanned.

13. Latent footwear impressions Powders Footwears in blood