Boston marathon bomber involved in 2011 triple homicide "Information and evidence tending to show that Tamerlan Tsarnaev participated in a triple homicide in 2011," a recent court motion read. By Brooks Hays | Oct. 12, 2014 at 2:35 PM | 3 Comments BOSTON, Oct. 12 (UPI) -- Accused terrorist Dzhokhar Tsarnaev apparently knew of the involvement Tamerlan Tsarnaev, his older brother and Boston Marathon bombing accomplice, in the killing of three Massachusetts men in 2011. According to a motion filed Friday by Tsarnaev's defense team in U.S. District Court: "The government disclosed that an identified witness would be prepared to testify" to Dzhokhar's knowledge of his brother's involvement in the grisly slayings. Defense lawyers filed the motion in order to gain access to documents relative to the 2011 case. Such evidence, they argue, could be vital in demonstrating the relative culpability of the two brothers. The defense team has made clear its intention to argue that Tamerlan was the dominant perpetrator. Tamerlan, the elder of the two brothers, was killed in a shootout with cops several days after the Boston Marathon bombing that killed three and injured 260. A friend of Tamerlan reportedly implicated him in the triple homicide only moments before his death. "Information and evidence tending to show that Tamerlan Tsarnaev participated in a triple homicide in 2011, and information depicting the brutality of those murders, is critical to the defense team," the motion read. If proven credible, the evidence could offer closure to a triple homicide case that went quickly cold. On September 12, 2011, three local men -- Brandon Mess, 25, Erik Weissman, 31, and Raphael Teken, 37 -- were found with their necks slit and marijuana sprinkled over their bodies in an apartment in Waltham, Massachusetts. Investigators assumed at the time that the killings were drug related.