Marathon bombing suspect wants access to records implicating brother in 2011 triple killing

FILE - This undated file photo, provided April 19, 2013, by the Federal Bureau of Investigation shows Dzhokhar Tsarnaev, surviving suspect in the Boston Marathon bombings. Tsarnaev, who faces a potential death penalty, is fighting to get access to investigative records that implicate his dead older brother in a triple slaying in 2011. In a filing this week in federal court, prosecutors say they have alerted Dzhokhar Tsarnaev that a friend alleges that Tsarnaev's older brother, Tamerlan, participated in the killings. The friend, Ibragim Todashev was later shot to death in Florida while being questioned by authorities. The younger Tsarnaev's lawyers have argued that evidence about his brother's involvement in the triple killings provides "mitigating information" that is critical to his defense. (AP Photo/Federal Bureau of Investigation, File) (The Associated Press)

FILE - In this Feb. 17, 2010, file photo, Tamerlan Tsarnaev smiles after accepting the trophy for winning the 2010 New England Golden Gloves Championship in Lowell, Mass. Prosecutors in the case against Boston Marathon bombing suspect Dzhokhar Tsarnaev, Tamerlan's brother, say a man shot to death during questioning by an agent in Florida told investigators that Tamerlan had been involved in a triple homicide (AP Photo/The Lowell Sun, Julia Malakie File) MANDATORY CREDIT (The Associated Press)

This May 4, 2013 police mugshot provided by the Orange County Corrections Department in Orlando, Fla., shows Ibragim Todashev after his arrest for aggravated battery in Orlando. Todashev, who was being questioned in Orlando by authorities in the Boston bombing probe, was fatally shot Wednesday, May 22, 2013 when he initiated a violent confrontation, FBI officials said. According to a filing made Monday, Oct. 23, 2013, Ibragim Todashev told investigators that Tamerlan Tsarnaev, the slain Boston Marathon bombing suspect, participated in a triple killing in Waltham, Mass. on Sept. 11, 2011. (AP Photo/Orange County Corrections Department) (The Associated Press)

The surviving Boston Marathon bombing suspect, who faces a potential death penalty, is fighting to get access to investigative records that implicate his dead brother in a triple slaying in 2011.

In a filing this week in federal court, prosecutors say they have alerted Dzhokhar Tsarnaev (joh-HAHR' tsahr-NEYE'-ehv) that a friend alleges that Tsarnaev's older brother, Tamerlan, participated in the killings.

The friend, Ibragim Todashev (IH'-bruh-heem TOH'-duh-shehv), was shot to death later in Florida while being questioned by authorities.

The younger Tsarnaev's lawyers have argued that evidence about his brother's involvement in the triple killings provides "mitigating information" that is critical to his defense.

But prosecutors argue it is an ongoing investigation that could be harmed by such a disclosure.

The Middlesex district attorney's office would not comment on the filing.