Abstract: Experiments were conducted on a human cadaver in August of 2004 at the Arapahoe County Coroner’s Office in Centennial, Colorado. An electrostatic dust print lifter (ESDL) was used to lift dusty shoe impressions from human skin. Shoe impressions of varied quality were tested with two commonly used ESDLs. All experiments support the use of this method for recovering dusty impressions from human skin.

Introduction

In August 2004, the authors conducted some controlled experiments with a human cadaver to deter mine whether dusty or soiled shoe impressions could be lifted from human skin using an electrostatic dust print lifter. All experiments were conducted at the Araphahoe County Coroner’s Office in Centennial, Colorado.

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 [1]. 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. Note: The medical examiner’s office should be contacted prior to performing any examination on the body. There are some jurisdictions that do not permit the crime scene investigator to do anything to the body without the Medical Examiner’s permission.

Tovar [2] 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.

Several types of manufactured lifting devices are available. A Kinderprint model 3C and a Sirchie model ESP900 were used for all experiments. The Kinderprint model is a larger unit with external electrical cable probes. The Sirchie model has internal probes and is a hand-held unit. Both units operate in a similar manner and produced very similar results. The metallic lifting sheets were placed on the body and secured in place with drafting dots (masking tape). The grounding plate or film was secured in a similar manner adjacent to the lifting sheet. The lifting sheet was oriented along the long axis of the leg. Because the arms and legs represented an arch, the film was rolled from the apex of the arch outward to minimize any air voids caused by the inability to gain a perfectly f lat contact between the skin and the lifting film.

Results

Figures 1 and 2 show dusty impressions on the cadaver prior to lifting. The reader will note that the light impression is difficult to see and may be difficult to photograph for a meaningful analysis with a suspect shoe. Figures 3 and 4 show the static dust lifts taken from each impression area. The quality of the impressions was very good and showed individual characteristics that could be used for an identification (Figure 5). All test impressions were successfully lifted from the cadaver. Second lifts were successful on the legs with minimal loss of detail. Secondary lifts were not attempted with the trunk or arms. An important observation from the experiments was that body hair and foreign debris could leave artifacts on the lifting film that could be mistaken as defects in the outsole. Good-quality initial photographs and notation of the condition of the skin in the impression area will be invaluable to the footwear analyst.

Figure 1 Light dust impression on human cadaver leg.		Figure 2 Heavy dust impression on human cadaver leg.

Figure 3 Static dust lift of light impression.		Figure 4 Static dust lift of heavy impression.

Figure 5

Close-up of defect details in heavy impression lift.

Discussion

Although electrostatic dust print lifters have been used successfully on a variety of surfaces, the authors could not find a published report of successfully recovering impressions from human skin. These experiments demonstrate that the use of an ESDL may allow for the recovery of latent and patent dusty impressions from human skin. Field processing, prior to the transportation of the body, may yield the best results under most circumstances. Investigators should consider the use of this device on the victim’s exposed skin in cases of kicking, stomping, restraint by footwear, or tire roll over. This technique is not recommended for use on living subjects. Similar experiments or successful case studies should be reported to expand our knowledge in applying this technique.

For further information, please contact:


Thomas W. Adair
Senior Criminalist
Westminster Police Department
9110 Yates Street
Westminster, CO 80031
303-430-2400 x4269
303-487-4154 FAX
tadair@ci.westminster.co.us

References

1. Bodziak, W. Footwear Impression Evidence, 1st ed.; CRC Press: Boca Raton, FL. 1995; pp 105-117.
   
   
2. Tovar, R. M. The Use of Electrostatic Equipment to Retrieve Impressions from the Human Body. J. For. Ident. 2004, 5 (5), 530-533.