Need to Know: Identifying a killer using just eight skin cells

On this week’s “TechKnow,” Crystal Dilworth explores innovative new crime scene technology that’s helping law enforcement solve more cases. Some methods, like “touch DNA,” are helping police tackle cases that have remained unsolved for years or even decades. Early years of DNA analysis required quarter-sized samples of blood in order to perform analysis. Over the years, the necessary sample size diminished in size, until all that was needed was visible blood in order to extract and test for DNA. Touch DNA takes genetic analysis to the next level, giving scientists and crime scene investigators the ability to find DNA evidence in the unseen.

M-Vac Systems CEO Jared Bradley demonstrates the M-Vac touch DNA collection system for TechKnow contributor Crystal Dilworth.

Touch DNA is a method of DNA collection and analysis that requires as little as seven or eight skin cells from the outermost layer of the epidermis. After the cells are collected, scientists use a polymerase chain reaction to duplicate the cells many times over. Then, fluorescent compounds highlight the 13 specific DNA locations that give a specific genetic profile of the person—enough to match them in a database, but without any information about race, gender, or personal health.

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In a process that can manage such a small DNA sample, collection is key. The M-Vac uses a wet vacuuming method to extract tiny skin cells from clothing, carpets, even porous surfaces like rocks and cement.