Did Tamerlan Tsarnaev commit brutal, drug-related triple murder two years before Boston Marathon bombing?

Federal prosecutors officially name deceased Tsarnaev as a suspect in the slayings

Tamerlan Tsarnaev (AP)

Federal prosecutors have named Tamerlan Tsarnaev as a suspect in a brutal drug-related triple murder that took place two years before he was shot dead by police while on the run following the Boston Marathon bombings.

According to a file registered on Monday, Tsarnaev was named as a participant in the killing by Ibragim Todashev – a 27-year-old mixed martial arts fighter who was shot dead by state troopers on May 13 this year after “turning violent” during questioning over the triple homicide.

The brutal murders took place in the city of Waltham, Massachusetts on 11 September 2011, with 25-year-old Brendan Mess – a boxer previously described as Tsarnaev’s “only American friend” – among the victims.

Mess, 31-year-old Erik Weissman and 37-year-old Raphael Tekken were found in an apartment with their throats with such force that all three were almost decapitated. The bodies had reportedly been mutilated and thousands of dollars in cash and marijuana found scattered over their remains.

The formal filing of the report is an attempt by prosecutors to prevent lawyers representing Tsarnaev’s younger brother and fellow Boston bombing suspect Dzokhar accessing investigative documents related to the triple murder.

The report stated: “The government has already disclosed to [Dzokhar] Tsarnaev that, according to Todashev, Tamerlan Tsarnaev participated in the Waltham triple homicide”.

It added: “Any benefit to [Dzokhar] Tsarnaev of knowing more about the precise 'nature and extent' of his brother's involvement does not outweigh the potential harm of exposing details of an ongoing investigation into an extremely serious crime, especially at this stage of the proceeding”.

Prosecutors confirmed that their attempt to prevent access to the information came because they feel the only time Tamerlan Tsarnaev’s previous criminal history would be relevant to Dzokhar Tsarnaev’s case would be at a potential sentencing hearing – not during the trial itself.

20-year-old Dzokhar Tsarnaev – an ethnic Chechen who moved to the US with his family aged eight - is accused of planning and carrying out the Boston Marathon bombings along with his 26-year-old brother on April 15 this year.

He faces 30 federal charges – including using a weapon of mass destruction -and 16 other charges. If found guilty Tsarnaev may face the death penalty.

Three people were killed in the twin explosions, which occurred close to the finishing line on Boston’s Boylston Street just as thousands of competitors were finishing the marathon. 280 people were injured in the blasts.

Tamerlan Tsarnaev was killed several days after the bombings after police tracked the suspects down to the sleepy Boston suburb Watertown and a large gun battle took place. Dzokhar Tsarnaev escaped but was found unarmed and badly wounded several days later, hiding nearby in a boat parked on a trailer.