Ibragim Todashev, 27, was shot and killed by an FBI agent after being questioned about his connection to Boston Marathon bombing suspect Tamerlan Tsarnaev.

According to NBC News, Todashev attacked the FBI agent with a knife and was shot dead in his Orlando, Fla., apartment. What do we know so far about Todashev and his connection to Tsarnaev? Here, a brief guide:

1. He confessed to being involved in a 2011 triple-homicide
Investigators have been probing the role Tamerlan and Dzhokhar Tsarnaev might have played in an unsolved triple homicide in 2011. According to ABC News, the case involves Brendan Mess, Tamerlan's former roommate and boxing partner, who was found with two other men in an apartment in Waltham, Mass., with their throats cut and seven pounds of marijuana dumped on their bodies.

At the time, police were puzzled by the lack of evidence of a forced entry and the $5,000 in cash that was left behind. NBC News reports that Todashev confessed to involvement in the case and was about to sign a written statement right before he got violent.

On Wednesday afternoon, it was revealed that investigators believe Tamerlan and Todashev were attempting a drug rip-off but decided to kill the three men once they realized that they would be able to identify them, according to NBC News.

2. He knew Tamerlan — but they weren't that close
According to The Wall Street Journal, Anzor Tsarnaev, father of the Boston bombing suspects, claimed that "Tamerlan and Mr. Todashev weren't close friends but knew one another because the Chechen disapora in the Boston area is a small one."

Anzor said that Tamerlan and Todashev were both into boxing and met several times at events. Khusn Taramiv, a friend of Todashev, told WESH-TV Orlando that Todashev was being investigated by the FBI because of the time he spent in Boston training in mixed martial arts with Tamerlan.

3. He was planning to visit Chechnya
Taramiv told Central Florida News 13 that Todashev thought Tuesday night would be the last time he was questioned by the FBI because he was supposed to catch a flight to Chechnya on Wednesday with a ticket he bought before the Boston Marathon bombings.

"They've been pushing him. They say, 'don't leave, don't leave,' so he decided to stay," Taramiv told Central Florida News 13. "But we had a feeling, worst case scenario something like that was going to happen."

4. He was arrested on May 4 for aggravated battery
According to an arrest affidavit acquired by WESH-TV, Todashev was arrested at the Premium Outlets after a father and son "got in his face" over a parking spot, resulting in an altercation that left the father covered in a "considerable amount of blood" and the son with a split lip, lost teeth, and a head injury.