Dzhokhar Tsarnaev, 19, who once lived in the Russian region of Dagestan close to Chechnyawas identified on Friday (April 19) as a surviving suspect in the Boston Marathon explosions earlier this week.

A national security official confirmed the identities of Dzhokhar Tsarnaev and his brother Tamerlan Tsarnaev as the Boston suspects.

On his profile page on the Russian social networking site, the suspect spelled his name as "Djohar Tsarnaev" and listed "Islam" and "Career and money" as his main concerns in life.

The profile says he attended School No. 1 in Dagestan's regional centre of Makhachkala, as well as Cambridge Ringe & Latin School in Boston.

Russia is battling an Islamist insurgency in Dagestan and other North Caucasus provinces that is rooted in two post-Soviet wars in Chechnya, which borders Dagestan.

Police killed one suspect in the Boston Marathon bombing during a shootout and were engaged in a house-to-house search for a second man on Friday in the Boston suburb of Watertown after a bloody night of shooting and explosions in the city's streets.

During the night a university police officer was killed, a transit police officer was wounded, and police say the suspects carjacked a vehicle before leading police on a chase that ended with one suspect shot dead.

Police said the suspect they were seeking was the man shown wearing a white cap in surveillance pictures released on Thursday (April 18) night which had been taken shortly before explosions on Monday (April 15) that killed three people and wounded 176 at the finish of the Boston Marathon.

Presented by Adam Justice