Friend of Tamerlan Tsarnaev and Person of Interest in 2011 Waltham Triple Homicide Shot and Killed by FBI

A friend of Boston Marathon bombing suspect Tamerlan Tsarnaev was shot killed by FBI agents at an apartment complex near Orlando, FL last month.

The shooting happened inside an Orlando apartment complex as an FBI agent and Massachusetts State Police detectives were questioning Ibragim Todashev about his friendship with Tsarnaev.

Law enforcement sources said the two Chechen immigrants once trained together at a Boston area gym. But evidence also suggests a criminal connection, involvement in a grisly triple murder that occurred in September 2011, in Waltham, Massachusetts.

Three men, including one who trained at the same gym, were found with their throats cut, their bodies had been covered with marijuana and thousands of dollars in cash. No one has been charged.

But sources say during questioning Tuesday night, Todashev implicated himself and Tamerlan Tsarnaev in the killings. As investigators pushed at him towards a confession, he snapped, reported Orr.

Law enforcement officials say the 27-year-old mixed martial arts fighter made a move that threatened the investigators. The FBI agent, who suffered cuts in the altercation, shot and killed Todashev.

The FBI became interested in him after phone records suggested a connection to Tamerlan Tsarnaev. Over several weeks agents kept tabs on Todashev and questioned him a handful of times. The FBI found nothing connecting Todashev to the Boston attacks.

Todashev, who lived in the u.s. for the past several years, was arrested two weeks ago on an aggravated battery charge. But now investigators want to find out if he had any connections at all to anything worse, including radical extremists overseas.

Earlier, CBS News senior correspondent John Miller reported that Todashev was a mixed-martial-arts fighter. Fighting was at least one interest that Todashev shared with Tamerlan Tsarnaev, who was once a boxer.

Miller also reported that Todashev had been to Chechnya before and was scheduled to return to Chechnya this week but canceled his flight.

While Todashev wasn't considered a suspect in the April 15th bombing of the Boston Marathon finish line, authorities believed that both Todashev and the older Tsarnaev brother were involved in the September 2011 triple slaying of Raphael Teken, Brendan Mess and Erik Weissman at their Waltham, MA apartment.

Todashev was granted permanent legal status to the USA in February, despite a 2010 arrest for assault after a traffic accident. Last month, Todashev was arrested at gunpoint in Florida after allegedly beating up a man in a parking lot.