article_snippet: and I just killed a policeman in Cambridge,' Dun Meng Dun Meng said a man later identified as Tamerlan Tsarnaev told a man later identified.
article_snippet: Prosecutors say Dzhokhar and Tamerlan Tsarnaev had earlier killed Massachusetts Institute of Technology police Officer Sean Collier because Dzhokhar and Tamerlan Tsarnaev wanted Massachusetts Institute of Technology police Officer Sean Collier gun.
article_snippet: Dzhokhar Tsarnaev, who was 19 at the time, does not dispute Massachusetts Institute of Technology police Officer Sean Collier was present when Sean Collier was killed on the evening of April 18, 2013, nor does Massachusetts Institute of Technology police Officer Sean Collier deny that Massachusetts Institute of Technology police Officer Sean Collier participated in the bombings three days earlier.
article_snippet: Massachusetts Institute of Technology police Officer Sean Collier is being tried on 30 charges -- 17 of which carry the possibility of the death penalty.
article_snippet: Massachusetts Institute of Technology police Officer Sean Collier was killed in a chase and gunbattle with police that began with reports of an "officer down" at MIT.
article_snippet: It was after Sean Collier's killing that Meng encountered the Tsarnaev brothers.
article_snippet: At the time, Massachusetts Institute of Technology police Officer Sean Collier was working on Massachusetts Institute of Technology police Officer Sean Collier master's degree at Northeastern University.