US investigators tell sources that female DNA has been found on one of the two bombs that exploded at the Boston Marathon on April 15.
CBS News and the Wall Street Journal confirmed that it is unclear if the DNA was from a spectator at the race, someone who sold the bomb materials or from a woman who could have helped suspects Dzhokhar and Tamerlan Tsarnaev in the attacks.
On Monday, FBI agents interviewed Katherine Russell, the widow of accused bomber Tamerlan Tsarnaev, the elder of the two brothers, who died after a shootout with police in the days after the bombings.
While she is not a suspect in the attacks, authorities did collect a sample of Russell's DNA.
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In other case developments, death penalty lawyer Judy Clarke joined the defense team representing the remaining Boston bombing suspect 19-year-old Dzhokhar Tsarnaev.
Tsarnaev is at Federal Medical Center Devens, a Federal Bureau of Prisons facility in Massachusetts that holds detainees who need medical care. He has been charged with using a weapon of mass destruction in the attacks which killed three people and injured over 260 others.
Clarke's previous high-profile clients include Unabomber Ted Kaczynski and Arizona shooter Jared Loughner.