Saliva from cheese bite yields DNA profile of burglar: a case report

Abstract

Physical evidence in the form of a high quality bite mark was discovered on a piece of yellow cheese found at the scene of a crime. The cheese had been frozen by police for 10 days after recovery and before submission to the laboratory for testing. The double swab technique was used to collect DNA samples. A sample of the suspect’s blood was obtained. Using PCR-based DNA typing at ten STR loci, (Profiler Plus, Perkin Elmer-Applied Biosystems) it was determined that the DNA from the cheese originated from the suspect. This case illustrates the importance of a) always considering human bite marks as both physical and biological evidence, and b) attempting DNA recovery in any case in which minute traces of saliva may be present, even in situations involving bacteria-rich foods.