The Use of Electrostatic Equipment to Retrieve Impressions from the Human Body

Abstract: Most articles submitted to forensic journals contain success stories. Unfortunately, this one does not, but it does demonstrate the viability of an electrostatic technique for retrieving impressions from human skin in certain situations. Most uses of electrostatic equipment focus on the retrieval of impressions made on hard surfaces, such as the impressions left on hard surfaces by dirt or dust from the soles and heels of shoes. In addition to its use for retrieving impressions left on hard surfaces, electrostatic equipment can also be considered for the examination of impressions left on human skin.

Case History

In August of 2002, sometime after twelve midnight, a worker found the dead body of a female lying in a field used by garbage trucks. The victim was lying facedown about 160 feet from a main roadway and about 100 feet into a covelike clearing that was surrounded by bushes. The physical evidence was minimal. No normal lighting existed, and the use of handheld lighting revealed no viable tire tracks or disturbances in the dirt and grass surrounding the victim.

The unknown female victim was turned over carefully. She had bruising around the forehead and eyes, with some blood and fluids draining from both her mouth and nose, and she appeared to have been beaten. When the body was turned over, the victim's blouse moved slightly above her pants and exposed her abdominal area. Some impressions were observed on the abdomen at this time.

Equipment

The procedure was conducted using a Kinderprint Electrostatic Dust Print Lifter portable unit, fully charged with a 120V AC / 12V DC wall unit.

Process

The origin of the impressions on the subject's abdomen could not be determined. When viewed in the dark with artificial lighting, the impressions appeared to have been caused by some form of dirt (possibly from a shoe). They did not appear to be due to any contusion left on the body. If the impressions had been caused by a contusion, different assessment and lifting techniques would have been considered.

Many print retrieval techniques have been proposed to retrieve impressions from human skin. However, utilizing gel or other retrieval techniques may require some form of pressure to be placed on the victim's body, which may disturb trace evidence and skin. Movement or pressure may cause a disturbance to the body or cause the impression to settle, thus possibly distorting the impression or destroying it altogether. The use of the electrostatic process minimizes skin disturbances.

The medical examiner's office was notified regarding the use of the electrostatic process as a possible technique for retrieving impressions from the victim's abdomen without disturbing the body or any possible trace evidence. The medical examiner's office authorized the forensic investigator to proceed with the electrostatic technique.

The victim was deep in a cove hundreds of feet away from the forensic investigator's vehicle. So as not to disturb the area around the victim, the battery power pack of the electrostatic system was used because of the awkward location of the body and the fact that no electrical wiring could be used with the existing forensic equipment. The forensic investigator used the same pathway to and from his vehicle at the scene near and around the victim to maintain the original condition of the surrounding area.

A piece of film paper about eight inches wide and ten inches high was placed, shiny side up, on the victim's abdomen covering the area of the noted impressions. The film paper was matted down by hand. A metal contact board was placed just below the abdomen area. The connectors on the metal contact board were secured to the film paper and the power was turned on. A low voltage was used initially to begin to secure the film paper to the subject's skin. As the paper began to adhere to the abdomen area, the voltage was increased. After about one and one-half minutes, the voltage was turned off, and the film sheet was removed after allowing a few seconds more for the electrical current to dissipate.

The film sheet was placed in a legal-sized manila folder (suggested by Bodziak, because the manila folder will not attract dust as a pizza-type box will) [1]. Upon observation at the scene and in the home office, impressions could be seen on the film when directing the light from a flashlight at an oblique angle of about 20 to 30 degrees. The film sheet was then packaged and forwarded to the Illinois State Police Crime Laboratory.

Summary

When checking with the Illinois State Police Crime Laboratory to assess whether any impressions were identifiable, I was informed that no viable comparison could be made from the retrieved impressions.

Unfortunately, during the retrieval process, air pockets formed because of the curvature of the abdomen area of the victim. To avoid this problem in future procedures, I suggest placing tape (possibly duct tape, because of its greater adhesiveness) on the outer edge of the film sheet to create a tighter seal on the subject's skin. In discussing the electrostatic process, the Illinois State Lab's latent print experts also suggested placing the film on the abdomen and using masking or duck tape to secure the edges of the outer perimeter of the film sheet, thereby making a tighter seal on the skin [2]. In addition, a stronger connection and seal might be secured by using the main electrostatic component of the print lifter connected to an electrical outlet, which produces a stronger electric current than the portable unit. When using the portable unit, even though the electric current was increased from low to high, the current did not appear to be strong enough to make a tight seal on the skin because of the curvature of the subject's abdomen.

Limitations can be seen in this process, depending on the type of impressions left on deceased individuals. However, if a dirt-type impression is seen on the skin, as in this case, the use of the electrostatic dust print lifting process may be a viable technique for retrieving impressions from the skin of deceased individuals, especially those found in isolated locations. This technique does appear to minimize any disturbance or distortion of the skin. It also enables a proactive lifting process to be implemented before any type of settling may occur that might minimize the evidentiary or probative value of the impression.

Continued research into the use of the electrostatic equipment to recover impressions from human skin is planned. That research will involve the testing of different types of dust (i.e., outdoor versus indoor) and shoeprint impressions.

For further information, please contact:


Robert M. Tovar
Mobile Crime Lab
Chicago Police Department
PO Box 4476
Chicago, IL 60680
cptmidnt@rcn.com

References

1. Bodziak, W. J. Footwear Impression Evidence: Detection, Recovery and Examination, 2nd ed.; CRC Press: Boca Raton, FL, 2000; pp 101-115.
   
   
2. Illinois State Police Crime Laboratory, Chicago, IL. Personal communication, 2003.

*From the Journal of Forensic Identification Vol. 54, No. 5, September/October 2004
The Official Publication of the International Association for Identification
"Reproduction of the Journal of Forensic Identification, in whole or in part, for noncommercial, educational use is permitted provided proper citation of the source is noted. Reproduction for any other use is prohibited without prior written permission. Requests for permission may be addressed to the editor (of the Journal of Forensic Identification -- jfieditor@theiai.org)."

Article posted: April 22, 2010