Filing: Witness can testify marathon bombing suspect knew of brother's role in 2011 slayings

Lawyers for Boston Marathon bombing suspect Dzhokhar Tsarnaev (joh-HAHR' tsahr-NEYE'-ehv) say a prosecution witness is prepared to testify Tsarnaev knew his older brother was involved in a 2011 triple slaying.

The information was revealed in a court filing by the defense late Friday. The filing seeks a number of items from prosecutors, including any evidence of Tamerlan Tsarnaev's involvement in the Waltham slayings. Prosecutors have previously declined to provide such information, saying it could jeopardize the ongoing investigation.

Dzhokhar Tsarnaev's lawyers say any evidence showing his now-deceased brother participated in the triple homicide is critical to their defense. In that case, three men's bodies were found sprinkled with marijuana, their throats slit.

Tsarnaev has pleaded not guilty in the 2013 bombings that killed three people and injured about 260 others.