Concerns When Using Examination Gloves at the Crime Scene

Abstract: Universal precautions that are used by forensic personnel at crime scenes are necessary to protect the crime scene processors from chemical and biological hazards. These precautions also serve to ensure that the scene is not contaminated by actions of the crime scene examiners. A particular type of glove that is routinely used in crime scene processing does protect against hazards but is not effective against scene contamination.

Introduction

Most individuals who are involved in the processing and reconstruction of crime scenes and associated evidence understand the absolute necessity to protect their skin from coming in contact with items of physical evidence. Additionally, crime scene personnel must not contaminate evidence that is being recovered during the collection and examination phases of the crime scene processing. For these reasons, gloves must be worn. However, many crime scene technicians and investigators have the misconception that gloves will prevent fingerprints from being left on handled items. Saferstein recommends that crime scene processors wear two pairs of latex gloves as a minimum [1]. This doubles the protection of both biohazard transmission and evidence contamination. Gerberth states that “approved disposable gloves” should be used at the crime scene [2]. Lee recommends latex gloves for the handling of evidence that is located in crime scenes [3]. Although latex gloves are often referred to in crime scene manuals and texts, some authors explain that liquid barrier rubber gloves are preferred [4].

Although the majority of texts recommend the use of latex gloves at the crime scene, latex presents a medical problem for some. Latex allergies are a danger to an increasing number of individuals [5]. This requires the selection of other gloves, most of which come from the medical profession. Various nitrile, latex, and vinyl examination gloves are popular in most crime scene processing units.

Research

In July 2004, 28 criminal forensic studies students from Florida Gulf Coast University participated in an experiment involving medical examination gloves and their ability to inadvertently contaminate evidence at a crime scene. The study was approved by the University Institutional Review Board. Medical verification was established to determine that none of the participants were allergic to any of the glove materials in the study. Allergies to latex were of particular concern.

Procedure

The participants were divided into four groups of seven each. Each group wore one of four types of popular examination gloves that are used by local crime scene units in South Florida (Fisherbrand Nitrile Examination Glove Catalog # 19-050-221D, Kimberly-Clark Safeskin Purple Nitrile Glove #50603, Oak Laboratory Handies Vinyl Gloves Item # 96-282, Ultra One Microf lex Powder-Free Latex Gloves #UL-315-L).

The authors (wearing cotton gloves) placed a single glove on the right hand of each participant, and then a paper bag was placed over the gloved hand. (The bag prevented the individual from contaminating the outside surface of the glove during the experiment.)

The gloves were worn continuously for one hour. At the end of one hour, the paper bags were removed and, without touching anything else, the individuals attempted to create fingerprints by pressing their fingers onto new white fingerprint lift cards. The pressure on the cards was a moderate touch, commensurate with the amount of pressure required to pick the cards up from the table. While wearing cotton gloves, the authors handled the target fingerprint lift cards by the edges to prevent contamination during the study.

The attempts to create latent prints continued every 15 minutes thereafter for two hours. The attempts were made by each participant, following the procedure of removing the paper bags from the gloved right hands. Each time, the hand was not allowed to contact anything other than the target fingerprint lift card. At the end of two hours and after the final attempt to place latent prints on the target cards, the participants were asked to run their gloved hand through their hair, and another attempt was made to place prints on the target fingerprint lift cards. All of the target cards (white) were processed using bichromatic gray magnetic fingerprint powder and a magnetic brush applicator.

Results

No impressions of any fingerprint patterns could be detected on any of the target cards that were tested during the first and second hours. Following the contamination of the gloves at the two-hour mark, all of them produced finger outlines (Table 1). Both Fisherbrand and Kimberly-Clark nitrile gloves produced the stipple pattern associated with their manufacture. The latex gloves only depicted the material folds and a smooth pattern outline with no ridge detail. The vinyl gloves showed identifiable detail each time. A close examination of the developed vinyl glove prints showed material folds, but this may be mistaken for tape folds during lifts.

On the target cards on which the Fisherbrand and Kimberly-Clark nitrile gloves were pressed, the stipple patterns of the glove were detected, but only after the intentional contamination (Figure 1). Nitrile gloves for both brands consistently left only stipple markings after contamination with the sebaceous secretions. Although this study did not address the issue of possibly identifying the individual glove through the stipple pattern, the manufacturing process may leave enough microscopic detail to individualize a glove. This is speculation that is based on similar findings on objects such as tire molds [6] in which mold defects and alignments cause individual characteristics in tire production. Research would have to include identifying the glove manufacturing process in detail to determine whether the stippling is random or from a fixed mold. For further study, it would be of some importance to determine whether the glove patterns on any stippled glove could be identified as having individual characteristics. Impressions made by the Ultra-One latex gloves showed no discernible pattern of either friction ridges or manufacturing markings. In the case of the nitrile and latex gloves, it was apparent that the impressions were from fingers, but no fingerprint ridge detail was observed. The Oak Laboratory vinyl gloves left smooth impressions on all seven target cards prior to contamination. No ridge detail could be observed.

The impressions that were made from the contaminated vinyl gloves left clear ridge detail on the target cards from all seven participants. The processed cards all showed pattern impressions (Figure 2). The target cards contained impressions of the vinyl folds and defects produced by the glove material along with friction ridge impressions from the fingerprints of the respective participants.

Conclusion

Vinyl gloves showed no signs of transference of palmar secretions through the barrier of the glove, because gloves that had not been contaminated on the outside with sebaceous secretions could not leave friction ridge impressions. However, when the outside surface became contaminated with a transference material, the glove membrane was sufficiently thin and of a density that allowed the glove to transfer the friction ridge shapes to the substrate. Although the glove may provide adequate protection from chemical or biological hazards for personnel, it is insufficient to protect the crime scene from friction ridge contamination.

Glove protection protocols to avoid latent print contamination is critical. Either a double glove should be worn or cotton gloves should be worn underneath the vinyl glove shell. The double glove method may be less comfortable because of the amount of heat it generates. Both the double glove method and the wearing of a cotton under-glove proved effective in keeping inadvertent latent prints by the crime scene personnel from contaminating the crime scene. Single glove wear, and in particular, vinyl examination glove wear, could significantly contaminate fingerprint evidence that is handled by crime scene processors at the scene.

Figure 1
Stipple pattern from a nitrile examination glove.
No discernable fingerprint ridges.

Figure 2
Developed latent fingerprint deposited through
contaminated examination glove (vinyl).
(Latex examination gloves produced similar examples.)

For further information, please contact:


David A. Lounsbury
Director, Institute for Forensic Excellence
Florida Gulf Coast University
10501 FGCU Boulevard South
Fort Myers, FL 33965-6565
(239) 590-7831
dlounsbu@fgcu.edu

References

1. Saferstein, R. Criminalistics: An Introduction to Forensic Science, 7th ed.; Prentice Hall: Upper Saddle River, NJ, 2001; p 49.
2. Geberth, V. J. The Homicide Crime Scene Search. In Practical Homicide Investigation: Tactics, Procedures, and Forensic Techniques, 3rd ed.; Geberth, V. J., Ed.; CRC Press: Boca Raton, FL, 1996; p 203.
3. Lee, H. C.; Palmbach, T.; Miller, M. T. Henry Lee’s Crime Scene Handbook; Academic Press: San Diego, 2001; pp 71-72.
4. Gardner, R. M. Practical Crime Scene Processing and Investigation; CRC Press: Boca Raton, FL, 2005; p 375.
5. Chowdhu r y, M. M. Epidemiology of Latex Allery. In Latex Intolerance: Basic Science, Epidemiology, Clinical Management; Chowdhury, M. M.; Mailbach, H. I., Eds.; CRC Press: Boca Raton, FL, 2005; pp 6-31.
6. McDonald, P. Tire Imprint Evidence; CRC Press: Boca Raton, FL, 1993; pp 78-79.

*From the Journal of Forensic Identification Vol. 56, No. 2, March/April 2006
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: February 25, 2008