(Update: The surviving suspect has been captured, and authorities now say the suspects were not involved in the 7-Eleven robbery.)
The manhunt for the surviving Boston bombing suspect is still on, but it isn't too early for cable news talking heads to speculate about whether the attack was carried out by two brothers or if they were part of a broader group.
One brother, Tamerlan Tsarnaev, 26, died last night after hours of violence that included the brothers robbing a 7-Eleven, killing an MIT police officer, severely wounding another officer, and committing a carjacking, authorities said.
Police are searching for the other brother, Dzhokhar Tsarnaev, 19. The brothers were living in Cambridge, just outside Boston, but several news outlets said they had ethnic roots in Chechnya. A man who said he was their uncle told Boston CBS affiliate WBZ that they were from Kyrgyzstan and had been in the U.S. for seven to eight years.
CNN also cited people who said they knew the younger brother in high school and described him as a normal teen. But several outlets said the older brother had written on Facebook, "I don't have a single American friend. I don't understand them."
Former United States Ambassador to the U.N. John Bolton told Fox News that the men may have been part of a "sleeper cell" and that others may be "waiting for the right moment" to strike.
"If they've been in the country for several years, I hate to put it this way, but it's good terrorist tradecraft," Bolton said. "They've completely scoped out the Boston area and they took a lot of preparation to do what they've done and that's why I think we need to be concerned that there may be others who have come to this country as students or under visas of one kind or another who are simply waiting for the right moment. ... These people are [getting] direction from others overseas and I think it shows their communication security was good. We had no advance warning of it."
Former FBI Assistant Director Tom Fuentes, meanwhile, told CNN the brothers did not appear to be working for a foreign group. He said the fact that they robbed a 7-Eleven Wednesday night seemed to suggest they had to "fundraise" because "they weren't sent here, funded, trained, ready to go directly from overseas." (Authorities said after his comments that the brothers had not actually robbed a 7-Eleven, as was initially reported.)
"From what I see, they probably weren't dispatched here," he said. "They've been in the U.S. a long time. So it doesn't appear that somebody overseas trained them and sent them on a mission. It seems that they were here, they were trying to assimilate into U.S. society and that didn't quite take. The other thing we don't know is the younger brother may have just come under the control of the older brother."
CNN's Jim Walsh and Erin Burnett stressed that the suspects' Chechen roots did not mean they had anything to do with Chechen separatists who have carried out past attacks in Russia. "It could just be two men inspired by something completely domestic," said Burnett.