Touch DNA refers to the DNA that is recovered from skin (epithelial) cells that is left behind when a person touches or comes into contact with items such as clothes, a weapon, or other objects.
A person sheds about 400,000 skin cells per day, but it is the lower skin cells that will provide the best DNA profile. These cells are typically recovered when force is used such as on the victim's clothes or at a crime scene after a struggle has occurred.
These epithelial cells can be lifted with a tape, swabbed with a Q-tip, or even scraped from the clothes of the victim, or objects. Even food can be scraped for skin cells. According to the Bode Technology Lab,
as little as 5 to 20 skin cells are all that is required to obtain a Touch DNA sample.
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