Federal Bureau of Investigation officials announced that the Florida man tied to one of the Boston bombing suspects was "about to sign a statement" admitting to a role in an unsolved triple murder in Massachusetts before he was shot and killed by an FBI agent Tuesday night.

Two people with direct knowledge of the case told ABC News that as Ibragim Todashev was being questioned by authorities concerning his ties with Boston bombing suspect Tamerlan Tsarnaev, he "just went crazy" and suddenly attacked the agent. Todashev was apparently about to sign a confession connecting himself and Tsarnaev to a gruesome triple murder in Massachusetts in 2011.

"The agent, two Mass­achusetts State Police troopers, and other law enforcement personnel were interviewing [Todashev] ... when a violent confrontation was initiated by the individual," the FBI said after the attack. "The individual was killed and the agent sustained non-life threatening 
injuries."

Law enforcement sources initially said Todashev stabbed the agent with a knife, but said Thursday there was confusion over what object Todashev used in the attack.

The Boston Herald reports that Todashev has a history of violence and was recently arrested for aggravated battery.

The FBI has sent a team of investigators to look into the fatal shooting. The investigators will examine how a man who was being interviewed for several hours came to possess a sharp object and why, even with several officers, plus other unidentified law enforcement personnel, lethal force was used to stop a knife attack by a suspected murderer with terrorist connections.