The presence of genetic material does not necessarily mean a woman helped build the pressure-cooker bombs, the official said, speaking on condition of anonymity.
The genetic material could have come from a woman who was in the room where the devices were built, or from a cashier at a store where one of the bomb parts was purchased, the official said. The test results have prompted investigators to look more closely at women who may have had contact with the alleged bombers, Tamerlan Tsarnaev and his younger brother Dzhokhar.
Investigators are collecting DNA samples from some women who were close to the pair to provide for a comparison. On Monday, investigators visited the Rhode Island home of the family of Katherine Russell, the widow of the elder brother, who was killed in a shootout with police on April 19. Dzhokhar Tsarnaev was wounded but captured, and faces federal charges of using a weapon of mass destruction. The two remote-controlled bombs killed three people and injured more than 260.
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Judy Clarke has been hired as the defence. She has defended Unabomber Ted Kaczynski, and Jared Loughner, who shot politician Gabrielle Giffords