Washington: An FBI agent shot and killed a 27-year-old alleged friend of slain Boston Marathon bombing suspect Tamerlan Tsarnaev in Florida, a day after questioning him as part of the investigation into the April 15 attack, media reports said.
The victim, identified as Ibragim Todashev, was shot at a condominium complex Wednesday in Orlando, Florida.
The FBI confirmed a man died while one of its agents was "conducting official duties".
"The agent, two Massachusetts State Police troopers, and other law enforcement personnel were interviewing an individual in connection with the Boston Marathon bombing investigation when a violent confrontation was initiated by the individual. During the confrontation, the individual was killed and the agent sustained non-life threatening injuries," said the FBI in a statement.
NBC News reported that Todashev had confessed to his involvement in a triple slaying in Massachusetts Sep 11, 2011.
Three men were found in an apartment with their throats slashed and their bodies covered with marijuana.
One of the murdered men was friends with Tsarnaev, who was also suspected of being involved in the murders.
Officials told NBC News that Todashev became violent as he was about to sign a written statement confessing to his involvement in the triple murder, and attacked the FBI agent with a knife.
Media reports, quoting Khusn Taramiv, a friend of the victim who was also questioned with Todashev in connection with the Boston bombing investigation, stated that Todashev, like Tsarnaev, originally hailed from Chechnya, a restive and mainly Muslim region of southern Russia.
Todashev had once lived in Boston and was a "casual friend" of Tsarnaev as both were involved at some point in mixed martial-arts fighting, WESH television station reported.
The report said Todashev and Tsarnaev had spoken by phone or Skype for about five minutes around one week before the April 15 twin bomb attacks in Boston that killed three people and wounded more than 260 others.
The FBI questioned both Todashev and Taramiv Tuesday. Taramiv told local media that investigators said they needed to question Todashev for several hours again Wednesday.
"They told me they're going to bring him back," Taramiv told WESH-TV. "They never brought him back. He felt inside he was going to get shot."
Tsarnaev was killed in a shootout with police near Boston several days after the Marathon bomb attack. His younger brother, Dzhokhar Tsarnaev, who is also suspected of having taken part in the attack, was captured wounded but alive. He remains hospitalized and is expected to face trial on terrorism charges.
US media reported last week that Dzhokhar Tsarnaev scrawled a message shortly before his capture - and has since reiterated to investigators - that the Boston attack was an act of retaliation for the US killing of Muslims in Afghanistan and Iraq.