Boston remains under lock down, as a manhunt continues for a young man described as a dangerous terrorist linked to the Boston Marathon bombings. Heavily armed police officers are going door to door with a focus on the Watertown area.  Police say the other marathon bombing suspect was killed overnight after the pair killed a campus police officer at MIT, injured a transit officer in a firefight and threw explosive devices at police during a getaway attempt.

The two suspects are being widely identified as brothers from the Russian Region near Chechyna, which has been plagued by an Islamic insurgency.  They’d been living as legal permanent residents of the U.S.  Initially the suspect killed was identified as being 20 years of age.  Now, he’s being referred to as 26 year old Tamerlan Tsarnaev.  The suspect still at large is his 19 year old brother Dzokhar Tsarnaev.  George McMasters says the younger suspect worked for him at the aquatic centre at Harvard University.  He tells CNN he was a conscientious worker.  “He showed up on time, watched the water.  He rotated from position to position fine, and got along well with the other students and swimmers there at the pool.  I don’t know a great deal about him.  I just know that he was one of the group that came down to the pool, a quiet young man.  And this is very surprising and shocking to see the destruction that he’s brought to the city.”

The Associated Press reached their father in Russia, who says Dzokhar is a second year medical student in the U.S. and describes him as a “true angel”.

The brothers lived together near Boston and had been in the U-S for about a decade.