Investigators say DNA found on a fragment of one of the Boston bombs is not a match with samples taken from the widow of Tamerlan Tsarnaev, reports NBC News. But that doesn't mean 24-year-old Katherine Russell is in the clear. In fact, authorities are "sharpening" their investigation of her, reports the Washington Post. Among the reasons: They found extremist material on her laptop, including al-Qaeda's Inspire magazine. What they don't know is whether she called up the material herself or whether her husband borrowed her computer to do so.
Dzhokhar Tsarnaev has told investigators that he and his brother built their bombs in Tamerlan's Cambridge apartment, which he shared with his wife and young daughter. Russell, who converted to Islam in 2009 and married Tamerlan the following year, is now staying with her parents in Rhode Island. She reportedly called her husband soon after the FBI released photos of the bombings suspects (initial reports suggested it was the other way around), but authorities still don't know what they said to each other. It's not helping her case that she didn't call police at that time. Also of note: Police are examining a section of woods near Dartmouth on the suspicion that the brothers tested explosives there. (Read more Katherine Russell stories.)