Beware of the Possibility of Fingerprinting Techniques Transferring DNA

• NCJ Number: 212651
• Journal: Journal of Forensic Sciences Volume: 50 Issue: 6 Dated: November 2005 Pages: 1417-1422
• Author(s): Roland A. H. van Oorschot Ph.D.; Sally Treadwell B.Sc.; James Beaurepaire B.Sc.; Nicole L. Holding B.Sc.; Robert J. Mitchell Ph.D.
• Date Published: November 2005
• Length: 6 pages
• Publication Format: Article; Correspondence
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

Four experiments tested the capacity of fingerprint brushes to collect and transfer DNA-containing material in the course of powdering for fingerprints.

Abstract

The testing used standard DNA extraction procedures and AmpF/STR Profiler Plus amplification and typing procedures. In the first experiment, 13 squirrel-hair fingerprint brushes of various history were each used over 2 clean sheets of plastic, using a separate aliquot of powder per brush. In the second experiment, saliva stain samples were prepared by spreading 40 ml saliva over an area of 2 x 2 cm on 19 sheets of plastic and allowed to dry overnight at room temperature. Samples from different individuals were used for different series. Fingerprint brushes were then used with powder in various combinations in applications to the areas with saliva stains. The third experiment consisted of two tests, one using varying amounts of black and white fingerprint powders added to separate DNA amplification mixes and the second using a squirrel-hair brush to powder six sheets of plastic that had been heavily contaminated with DNA from a single source. The fourth experiment used a sample (n=73) of squirrel-hair brushes in current use to test their potential for transferring DNA to a surface in the process of collecting a fingerprint. The details of methodology and findings are reported for each experiment. Overall, the tests show that fingerprint brushes can accumulate DNA from surfaces with which they come into contact, and they can also redeposit DNA-containing material to a number of subsequently brushed objects. The chance of this occurring increases after powdering biological samples, such as blood, saliva, skin, or fresh prints. The authors advocate caution when powdering prints from which DNA may also be collected, and they suggest options for consideration to limit the risk of transferred DNA contamination while fingerprinting. 4 tables and 15 references