NCJ Number
168694
Journal
Journal of Forensic Sciences Volume: 42 Issue: 2 Dated: (March 1997) Pages: 320-322
Date Published
1997
Length
3 pages
Annotation
This study assessed several techniques for collecting saliva from human skin and extracting DNA from the substrate.
Abstract
Human bite mark evidence is often found in violent crimes. Due to the difficulties of physically comparing an injury site on elastic and curved skin surfaces to the teeth of a suspect, this study considered using salivary DNA evidence to identify the bite perpetrator. Several techniques were evaluated to determine the best method of recovering saliva from human skin before extracting genomic DNA from the collection substrate. A classical stain recovery technique that uses a wet cotton swab was tested against one that uses a wet filter paper. Additionally, a new method, referred to as the double-swab technique (using a wet cotton swab followed by a dry cotton swab), was also assessed. After recovering a dried saliva stain, DNA was extracted by using the modified Chelex method, quantified using the slot-blot procedure, and amplified at three polymorphic loci. The double- swab technique showed the highest percentage recovery of saliva from human skin among the three methods studied. This technique is suggested as an improvement over the classical single wet cotton swab technique. 1 figure and 18 references