DA looks for links between bomb suspect Tamerlan Tsarnaev and 2011 triple murder

Investigators in a Boston suburb are looking into possible links between a suspect in last week's Boston Marathon bombing and an unsolved 2011 triple murder.

Marathon bombing suspect Tamerlan Tsarnaev, who was pronounced dead early Friday after a shootout with police, was a friend of one of three men found dead in an apartment in Waltham on Sept. 12, 2011, their necks slit and their bodies reportedly covered with marijuana.

Tsarnaev and his murdered friend, Brendan Mess, were both boxers.

Middlesex County District Attorney's Office spokeswoman MaryBeth Long said authorities are checking for any possible connection beteen Tsarnaev and the murders.

"We continue to follow all leads and will review any new information that may come to light in that case as a result of the investigation of bombing suspect Tamerlan Tsarnaev," Long said.

John Allan, owner of Wai Kru Mixed Martial Arts in Allston, told the Boston Globe that he had introduced Tsarnaev to Mess back in 2011. Allan described Tsarnaev as the "best boxer in Boston" but said he hadn't been back to the Wai Kru Mixed Martial Arts center in years -- at least not until this month, the Globe reported.

While Allan was on a trip to Thailand, he received an email from employees saying that Tsarnaev had showed up to the gym and had acted rude to other gym-goers. Allan said the incident was a sign that "something was up."

Click for more from the Boston Globe.

FoxNews.com's Cristina Corbin and the Associated Press contributed to this report.