More background on the brothers that several sources tell CNN are the suspects involved in Thursday night's shootings and police chase and Monday's Boston Marathon bombings:
The Tsarnaev brothers were Kyrgyz passport holders, and they used those passports when applying for green cards in the United States, an official in the central Asian republic of Kyrgyzstan said, according to CNN's Ivan Watson.
This doesn't mean they were born in Kyrgyzstan or that their family members were Kyrgyz natives. Many Caucasus refugees received passports or refugee status from surrounding countries.
[Updated 10:14 a.m. ET]
Some background on the brothers that several sources tell CNN are the suspects involved in Thursday night's shootings and police chase and Monday's Boston Marathon bombings:
Dzhokar Tsarnaev, 19, the marathon attack suspect now at large, came to the United States as a tourist in the early 2000s and asked for asylum while he was here, a federal source said. He was naturalized last year. Tamerlan, the 26-year-old brother who was killed overnight, came "a few years later" and was a green card holder, not a naturalized citizen, the source said, according to CNN's Mike Ahlers.
[Updated 10:02 a.m. ET]
We now have the name of he Massachusetts Institute of Technology police officer who was killed Thursday night. He was Sean Collier, 26, of Somerville, Massachusetts, according to the Middlesex District Attorney's Office.
[Updated 9:48 a.m. ET]
An aquatic director at Harvard University told CNN that he hired Dzhokar Tsarnaev as a lifeguard more than two years ago, but hasn't seen him for more than a year.
"He seemed like a very quiet, unassuming young man," the aquatic director, George McMasters, told CNN on Friday morning. "He showed up on time, watched the water, rotated from position to position fine, got along well with students and swimmers there at the pool."
[Updated 9:34 a.m. ET]
Boston police have released a new photo of Dzhokar Tsarnaev, the suspect still being sought in the Watertown area.
[Updated 9:31 a.m. ET]
The Boston bombings suspect who was killed in a confrontation with police overnight in the Boston area was wearing explosives and an explosive trigger when his body was recovered, a source briefed on the investigation says, according to CNN's Deborah Feyerick.
Several sources tell CNN that the dead suspect has been identified as Tamerlan Tsarnaev, 26, and the one still being sought in Watertown is Dzhokar Tsarnaev, 19.
Police have publicly said that the dead suspect is the man that the FBI previously identified as "Suspect No. 1" in the Boston Marathon bombings. They also have said publicly that the suspect that they chased and last saw in Watertown overnight is the man that the FBI said was "Suspect No. 2."
[Updated 9:16 a.m. ET]
The brothers suspected in the Boston Marathon attack haven't been connected to the Russian region of Chechnya for many years, the Chechen president's office said, according to the Interfax news agency.
The Tsarnaev family years ago moved out of Chechnya to another Russian region, lived some time in Kazakhstan, and then went to the United States, where the family members received a residence permit, the office said.
"Therefore, the individuals concerned did not live as adults in Chechnya," said Alvi Kamirov, press secretary for Chechnya's president.
Several sources tell CNN that the dead suspect has been identified as Tamerlan Tsarnaev, 26, and the one still being sought in Watertown is Dzhokar Tsarnaev, age 19.
[Updated 9:01 a.m. ET]
Boston police have now named the suspect that authorities have been seeking this morning. "Suspect identified as 19 year-old Dzhokar Tsarnaev of Cambridge. Suspect considered armed & dangerous," Boston police said on Twitter.