Boston Marathon bombing suspect Tamerlan Tsarnaev, left, and Ibragim Todashev, who was fatally shot in Orlando, Fla., May 22, 2013, when he initiated a violent confrontation, law-enforcement officials said. - Cambridge Police Department/AP/Orange County Corrections Department

There’s been speculation previously that Boston bombing suspect Tamerlan Tsarnaev might have been involved in an unsolved triple homicide in Waltham, Mass. in 2011, and this morning in Florida, FBI agents shot dead a Chechen man who allegedly confessed that he helped Tsarnaev commit the murders. CBS News has more details:

Law enforcement sources told Orr that the man, a Chechen identified as Ibragim Todashev, implicated himself and Tsarnaev to authorities in the 2011 killings in Waltham, Mass., under questioning Wednesday at Todashev’s apartment in Orlando, Fla. …

Sometime after midnight Wednesday morning in Orlando, an FBI special agent from the bureau’s Boston field office was accompanied by at least two troopers from the Massachusetts State Police and a Joint Terrorism Task Force agent to question Todashev, the sources said. The questioning primarily focused on the 2011 killings.

While the FBI’s investigation into Wednesday’s shooting is ongoing, the preliminary details are that after Todashev implicated himself and Tamerlan Tsarnaev he became angered when authorities pressed him for a full confession, the sources said. Todashev brandished a knife, prompting the officials to feel that their lives were in danger.

The FBI agent then shot Todashev and received some minor abrasions in the process, the sources said.

The Tsarnaev brothers and Todashev apparently knew the three people killed in Waltham, the sources said, describing the 2011 killings as brutal and grisly, with all three bodies nearly decapitated. The bodies had marijuana and thousands of dollars in cash sprinkled on them.