By Sid Perkins
From Washington, D.C., at a meeting of the American Academy of Forensic Sciences
Add flip-open cell phones to the list of crime-scene items that might harbor a suspect’s DNA.
After seeing media coverage of a crime in which a suspect had bled on a cell phone that he later dropped, Meghan J. McFadden, a molecular biologist at McMaster University in Hamilton, Ontario, wondered whether normal phone use would leave detectable traces of DNA. So she and colleague Margaret Wallace of the City University of New York analyzed the flip-open phones of 10 volunteers.
First, the researchers swabbed the surfaces of the phones in two spots: one on the outside, where the phone was held during use, and one near the ear speaker, which would be somewhat protected when the phone was folded shut. Then, they scrubbed the phones with a solution of 95 percent alcohol and returned them to the volunteers. One week later, McFadden and Wallace again swabbed the phones for DNA.
From each swab, researchers recovered DNA consistent with that of the phone’s owner. Samples taken from the outside of the phone typically produced a more complete DNA profile but also included genetic sequences that didn’t match the owner, possibly some that belonged to other people who had handled the phone.
Surprisingly, says McFadden, even the swabs rubbed on a phone immediately after it was supposedly cleaned with high-strength alcohol yielded DNA—a sign that suspects probably wouldn’t be able to use a simple scrubbing to destroy all the genetic material left on a phone.
