And neither were the fingerprints, but that won’t end the FBI’s interest in the widow of one of the Boston Marathon bombers. The bombs were built in relatively close quarters, CBS’ John Miller points out, and the sudden proliferation of pressure cookers, ball bearings, and fireworks must have raised some suspicions in Katherine Tsarnaev’s mind – if she saw them at all. That question, plus a phone call while Tamerlan was on the run, has investigators very interested in continuing to talk with Mrs. Tsarnaev … even if she’s not interested in talking with them:

I’m inclined to agree with Miller that the reported lack of cooperation is just an attorney doing his/her job in protecting a client. It’s not difficult to see how Katherine Russell Tsarnaev could become a suspect, if she’s not already one, and needs to protect herself from becoming further implicated in the plot. There are a lot of unanswered questions about her knowledge of Tamerlan’s plans — starting with his six-month absence in Dagestan that left her with a small child to care for all by herself.  How does a young wife justify that, unless she knows what her husband’s business will be on the trip?

And wouldn’t she have known that her husband had been plotting a suicide attack, at least initially?

Tsarnaev and his younger brother, Dzhokhar, initially planned to carry out a suicide-bomb attack on July 4, a U.S. law enforcement official regularly briefed on the Boston bombing investigation told CNN. The source said Dzhokhar Tsarnaev told investigators their bombs were ready earlier than they expected and they decided to move up the date.

Dzhokhar Tsarnaev told investigators that the Boston Marathon was chosen as a target only a day or two before the event, the source said.

It is unclear which specific event would have been targeted but one of the biggest July Fourth celebrations in the country is held in Boston. The annual Boston Pops Fireworks Spectacular hosts 500,000 spectators, according to the event’s website. It is televised live nationally on CBS.

And the FBI would really like to know what Katherine and Tamerlan discussed the day before the shootout that ended up making her a widow:

Meanwhile, investigators in the Boston bombing case want to find out what Tamerlan Tsarnaev and his wife discussed when he phoned her a few hours after the FBI released photos of him and his brother as suspects in the deadly attack, a separate law enforcement official said Thursday. …

The content of the phone conversation between Tamerlan Tsarnaev and his wife, Katherine Russell, has not been disclosed, but authorities want to discuss it with her, the law enforcement official said.

The official said investigators are seeking Russell’s cooperation in learning more about Tsarnaev’s activities and communications leading up to the attacks.

The DNA and fingerprint evidence may lead nowhere; the print could have come from someone who handled the pressure cooker at the factory or in a store, and the DNA could have come from one of the many victims of the Tsarnaevs.  The other questions surrounding Katherine Tsarnaev won’t be so easily dismissed.