A man carjacked by the accused Boston Marathon bombers is among those testifying today at the trial of the surviving Tsarnaev brother.

Dun Meng recounted the terrifying moment on April 18th, 2013 when Tamerlan Tsarnaev tapped on the window of his Mercedes and pulled out a gun. Meng told the jury the gunman claimed credit for the bombing and added "I just killed a policeman."

Tamerlan died later that night in a shootout with police in the Boston suburb of Watertown.

His 21-year-old brother Dzhokhar is facing a possible death penalty in the April 15th bombing that killed three people and injured 264 others.