The findings show that nonself DNA can be recovered and amplified from the skin surface of the neck and finger pads of adult volunteers using standard techniques equivalent to those used within British forensic casework. During the investigation of crimes such as assault, rape, or murder, DNA may be collected from the victim’s skin surface over areas in which physical contact has occurred. Under such a procedure, every allele observed in a resulting DNA profile must be assessed and the source determined. Once a mixed DNA profile has been observed and analyzed blind, reference profiles from the sample donor and all persons who are known to have had contact with the donor in the period leading up to the criminal incident will be compared to the mixture, so as to identify potential sources of observed nondonor contributors. DNA profile components that cannot be assigned to known sources may possibly come from the unknown perpetrator. The current study shows that such unknown DNA profile components may originate from innocent sources, unconnected to the criminal event being investigated. This may provide false evidence that can hinder the investigation. Sixteen female and 8 male volunteers--including single, married, and individuals with partners--were recruited in order to determine the levels of self and nonself DNA on their neck skin. Phase three directly examined the transfer of DNA from the finger pad to the surface of the neck. 6 tables, 3 figures, and 20 references