article_snippet: Video taken from above the site of Sean Collier's April 18 murder purports to show the Tsarnaev brothers (circled) rounding a corner toward Sean Collier's cruiser, at left (grab via WCVB)
article_snippet: Federal prosecutors contend Tsarnaev, who emigrated with his family from Chechnya a decade before the attack, was driven by an extremist view of Islam and a desire to take revenge on the United States for military campaigns in Muslim-dominated countries.
article_snippet: A graduate student at MIT, Nathan Harman, who was bicycling on campus the night of the murder, testified on Wednesday that he saw Tsarnaev leaning into the driver's side door of Sean Collier's car, but did not see the older sibling. '
article_snippet: ofTsarnaev withdrawing $800 from an ATM using a credit card he had just stolen during a carjacking three days after the bombings .
article_snippet: Harman said Harman assumed Tsarnaev was an MIT student. '
article_snippet: Tsarnaev, 21, is accused of killing three people and . injuring 264 with a pair of homemade bombs, as well as fatally .
article_snippet: older brother Tamerlan, who died four days after the bombing .
article_snippet: Federal prosecutors contend Tsarnaev, who emigrated with his .
article_snippet: family from Chechnya, was driven by an extremist view of Islam .
article_snippet: the hull of a boat in which Tsarnaev was hiding in Watertown, outside .
article_snippet: Boston, moments before Tsarnaev violent capture.