[Audio] Hello, and welcome to this mini teach on footwear marks..
[Audio] Classification of footwear marks. Footwear marks can be separated into different categories. Footwear marks can be latent or visible. A latent footwear mark can be described as not visible or needs enhancements and/or lighting to be visible. A visible footwear mark can be described as visible without enhancement..
[Audio] Footwear marks can be classified as positive or negative. Positive marks are where shoes leave marks by depositing contaminant off the bottom of the shoe onto a surface. Negative marks happen when shoes remove a contaminant, leaving a mark. Some examples of contaminants are paint, dust and mud..
[Audio] Footwear marks can either be 2D or 3D. 2D marks are formed on hard surfaces or are a soft surface laying on a hard surface. 3D marks are formed when the shoe is pressed onto a soft surface..
[Audio] Recovery of footwear marks. Footwear marks can be recovered in many different ways: ESLA, casting and gel lifters. Each method can be used in different circumstances and all have their own benefits. ESLA stands for Electrostatic Lifting Apparatus, it uses electrostatic charge and double sided foil to attract dust particles. The ESLA can be used on many surfaces. Casting is used for 3D marks. Pre-weighed plaster and water are mixed and poured into a 3D mark. Once hardened, the plaster is removed, this is a destructive technique. Gel lifters can be used to lift footwear marks like the ESLA, however gel lifters can be used in wet conditions..
[Audio] Enhancement of footwear marks. Enhancement of footwear marks can be done using magneta flake powder, as well as aluminium powder. These methods allow for increased detail to be seen. After marks are enhanced, pictures should be taken before lifting them using a gel lifter..
[Audio] Further enhancement of footwear marks. Footwear marks can be further enhanced via a couple of different methods, both on scene, as well as in the lab. Acid dyes are the best method of developing footwear marks even more, they allow for more detail to be seen, small details like damage to a shoe can help determine one pair from another. A slightly less effective method is the use of LCV ( Leuco Crystal Violet)..
[Audio] Packaging retrieved footwear marks. Gel lifters can be packaged by replacing the acetate front sheet and putting them in evidence bags. Cast should be left to set at the scene before removing carefully, making sure not to remove any soil, stones or other materials. Place the cast into a window cardboard box and leave for 24-48 hours to set properly in secure storage. After 24- 48 hours, pad the cast with tissue for protection and use a yellow exhibit label to secure the box. ESLA evidence can be packaged in a cardboard box, making sure to secure with tape. Any tape used must be signed and dated, written half on and half off the tape..
[Audio] Different uses of footwear mark evidence. Footwear mark evidence is very useful, it has many different uses. It can be used to link multiple scenes together. It can determine the movement throughout a crime scene. It allows you to determine the minimum number of people present. It can be used as supportive evidence to prove someone, or someone's footwear was present at a crime scene..
[Audio] Thank you for listening.. Thank you for listening.