SCOTT SIMON, HOST:
This is WEEKEND EDITION from NPR News. I'm Scott Simon. Law enforcement officials are getting a better idea of what may have transpired on the days leading up to the last month's Boston Marathon bombings, specifically where the two suspects, Dzhokhar and Tamerlan Tsarnaev, might have assembled their homemade bombs and whether anybody else was involved.
NPR's Dina Temple-Raston has been following this story and joins us. Dina, thanks for being with us.
DINA TEMPLE-RASTON, BYLINE: You're welcome.
SIMON: Worthy discovery?
TEMPLE-RASTON: Well, the big discovery has been these tests that indicated there was explosive residue in the kitchen and bathtub of Tamerlan Tsarnaev's home in Cambridge, Massachusetts, so officials think at least some portion of those pressure cooker bombs used in the attack were built in that apartment.
Tamerlan Tsarnaev, he's the 26-year-old older brother who died after a shootout with police after the attack. Well, he shared that apartment with his wife and child, so officials are taking a closer look at his wife, Katherine Russell, because they think it might have been hard to have missed something like that if she was home.
SIMON: Do they suspect she might have been in on the plot, or something else?
TEMPLE-RASTON: Well, they're trying to determine if either she was part of the plot or at the very least turned a blind eye to it. I mean, some of the things they're following up on are that she spoke to her husband by telephone after his picture appeared on television as a suspect. We don't know what they talked about, but we do know she didn't call police.
And then we heard this week that there was female DNA and a fingerprint on bomb fragments, but it turns out that those didn't belong to Katherine Russell, so police are still following up on that.
SIMON: Is Katherine Russell cooperating?
TEMPLE-RASTON: She was, but now apparently she's only speaking to police and FBI through her lawyers.
SIMON: There were reports this week, too, that the brothers apparently decided on the Boston Marathon as their target just a few days before the race?
TEMPLE-RASTON: Yes, we understand from law enforcement officials that Dzhokhar Tsarnaev, the surviving suspect, told the FBI that he and his brother had originally thought that they would launch an attack on the 4th of July in Boston, but they were able to make these bombs so quickly they decided on the Boston Marathon target instead.
And that's consistent with something else that we found out this week about the case, which is three of Dzhokhar's friends were arrested for obstruction of justice and for lying to federal agents, and officials say they were trying to help Dzhokhar after the attacks. And one of them apparently told the FBI that about a month before the attacks, Dzhokhar told him they knew how to make a bomb.
We also know now that is friends not only threw away Dzhokhar's backpack, but also grabbed his laptop from his dorm room and they've turned that over to the FBI.
SIMON: And does that affect how the FBI looks at what Dzhokhar was searching for and writing about just before the attack?
TEMPLE-RASTON: Well, one of the big things that's missing here is what led up to these attacks. Who else might have been involved? For example, where did they test the bomb? There might be an email on that computer that could provide a clue. Right now officials are out in the woods around Dartmouth, Massachusetts looking for places where the Tsarnaev brothers might have tested explosives.
They're going through police logs and they're looking for complaints about gunfire or explosions and they're trying to see if the two did in fact test those bombs here in the U.S. before the attack.
SIMON: NPR's counterterrorism correspondent, Dina Temple Raston. Thanks very much for being with us.
TEMPLE-RASTON: You're welcome. Transcript provided by NPR, Copyright NPR.