A Chechen man linked to one of the Boston Marathon bombing suspects was shot and killed early Wednesday in an unusual encounter with the FBI and other law enforcement officers inside his apartment in Orlando.

According to federal law enforcement officials, the man was being interviewed about whether he and Tamerlan Tsarnaev, one of the bombing suspects, were connected to a two-year-old triple slaying when he attacked an FBI agent and was shot and killed. There were conflicting accounts of what happened in the moments before the man was shot.

One federal law enforcement official said the man, a trained martial-arts fighter with one professional bout, was shot after trying to grab the FBI agent’s gun. Two other officials said the man reached for a knife and was shot as he attacked the agent. All three officials spoke on the condition of anonymity because the episode is under official review.

The man was identified as Ibragim Todashev, 27, a former Boston area resident who knew Tsarnaev from martial-arts and boxing circles. Todashev had recently moved to Orlando from Cambridge, Mass.

Law enforcement officials said Todashev was not a suspect in the bombing. Instead, they said, he was being interviewed about his possible role in a triple murder in Waltham, Mass., on Sept. 11, 2011. They said Todashev acknowledged involvement in the murders and implicated Tsarnaev in what the law enforcement officials described as a drug deal that went bad.

The FBI provided few details about the shooting, but the bizarre twist demonstrated the extent of the ongoing investigation into the April 15 marathon bombing which killed three people and injured more than 260.

Dozens of FBI agents and other law enforcement officers have been conducting interviews across the United States and in Russia with associates of Tsarnaev and his brother, Dzhokhar, to learn whether anyone else was associated with the Boston attack. The interviews have focused largely on people from the northern Caucasus area of Russia, where Tamerlan Tsarnaev spent six months in 2012. The Tsarnaev family has roots in Chechnya, and the FBI suspects he might have had contact with Islamic militants there.

Reached in the Russian republic of Dagestan, Anzor Tsarnaev, Tamerlan’s father, said his son knew Todashev and he believed the two had met while in the United States. “All Chechens are like relatives,” he said. “This is all so sad.”

Tamerlan Tsarnaev was killed in a shootout with police four days after the bombing. His brother was captured later that day and faces charges that could carry the death penalty. Before he was charged, Dzhokhar Tsarnaev told the FBI that no one else was involved in the plot and that he and his brother had acted out of anger over the U.S. conflicts in Iraq and Afghanistan.

Shortly after midnight Wednesday, the FBI agent, two Massachusetts State Police officers and other law enforcement personnel went to Todashev’s apartment in an area near Universal Studios to interview him about his relationship with Tsarnaev and their suspected ties to the Waltham murders.

The law enforcement officials said he was initially cooperative and appeared to be on the verge of signing a confession when the interview turned into a confrontation. The FBI agent sustained minor injuries.

Tsarnaev’s name had surfaced in earlier news reports about the Waltham slayings, which remain unsolved. He was friends with one of the victims, news outlets had reported.

Authorities say that the men died early Sept. 12, but relatives of at least one of the victims insist that the men were killed Sept. 11, the 10th anniversary of the attacks in New York and at the Pentagon.