Crime Scene Investigator Network Newsletter

Electrostatic dust print lifters (ESDLs) are commonly used in crime scene processing to lift latent and patent shoe impressions from a variety of porous and nonporous surfaces. Although there are several brands and configurations of ESDLs on the market today, they all share some common characteristics. ESDLs use a high voltage current to attract dust particles, comprising the impression, from various substrates to a metallic sheet film. These units use a grounding film, plate, or rod in close proximity to the lifting film to acquire the desired static charge that is necessary for successful transference of the impression. Once the unit’s electrical probe makes contact with the film, the static charge draws the film in contact with the substrate. A rubber roller pad is then used to smooth out the film and eliminate any air voids. (This should be done with care to avoid moving the film.) This process is considered to be nondestructive to the evidence and is therefore considered to be an ideal first process following traditional photography methods. This process is not recommended for lifting wet (e.g., blood or chemically treated) impressions on human skin. In addition, this search process must be conducted prior to the body’s being washed during normal autopsy procedures.

Tovar discussed the possibility of using an ESDL in lifting an impression from a human body. Although his results were negative, the techniques proposed by the author are similar to the ones used in these experiments. As such, these techniques should produce good results if a usable shoe impression is present to begin with. Our experiments tested shoe impressions; tire impressions should yield the same results because of the similar nature of the impression.

Materials and Methods
An adult male human cadaver was used for all experimentation. Death was from natural causes and there was no pre-existing trauma to the testing areas of the body. Tests were conducted on the arms, legs, and trunk of the cadaver. The cadaver was taken from refrigeration and kept at room temperature (68 ºF) for several hours. (Warming the body to room temperature is not required for the proper operation of the ESDL; however, it does make the skin more pliable and easy to work with when rolling out the lifting film.) Hi-Tec hiking boots with moderate wear were used for all impressions. The boots were worn while walking in the sally port garage of the coroner’s office to obtain a layer of dust on the outsole. Impressions were made by placing the boots in contact with the skin using both “heavy” and “light” pressure from the hand. Test impressions were allowed to sit for one hour prior to lifting attempts.

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