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

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 bee n 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 s amples. A sample of the suspect's blood was obtained. Using PCR-based DNA t yping at ten STR loci, (Profiler Plus, Perkin Elmer-Applied Biosystems) it was determined that the DNA from the cheese originated from the suspect. Th is case illustrates the importance of a) always considering human bite mark s 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 situat ions involving bacteria-rich foods.