A man shot dead by FBI agents investigating the Boston Marathon bombings reportedly admitted his involvement in an unsolved triple murder, along with bomb suspect Tamerlan Tsarnaev.
A friend of the dead man identified him as 27-year-old Ibragim Todashev, who had previously lived in Boston and knew Tsarnaev, the older of the two brothers suspected of planting two bombs at the marathon on April 15, killing three people and injuring 264 others.
NBC News reported that Todashev had confessed to his involvement in an unsolved 2011 triple homicide in a Boston suburb that investigators believe was drug related.
Authorities were investigating possible connections between Tsarnaev, who died in a shootout with police, and the 2011 incident.
Three men including a close friend of Tsarnaev were found stabbed in the neck in an apartment on September 12, 2011, in Waltham, Massachusetts. News reports said marijuana was strewn over their bodies.
Todashev was shot at an apartment complex near the Universal Studios theme park, where the FBI and members of other law enforcement agencies including the Massachusetts State Police were interviewing him about the marathon bombing.
"A violent confrontation was initiated by the individual," the FBI said.
A special agent, it said, "acting on the imminent threat posed by the individual, responded with deadly force. The individual was killed and the special agent was transported to the hospital with non-life-threatening injuries."
The possibility that Tsarnaev was connected to the Waltham murders is "being looked at seriously," said Republican Representative Peter King, chairman of the counter-terrorism and intelligence subcommittee of the House Homeland Security Committee.
Other US officials confirmed the investigation did involve Tsarnaev's possible role.
A source said, however, that while Tsarnaev's connection to the Waltham killings was actively under investigation, at this point there was no evidence to suggest the murders were linked to the Tsarnaev brothers' possible motives or actions in allegedly carrying out the marathon bombings.
A spokeswoman for the office of the District Attorney of Middlesex County, Massachusetts, where the murders occurred, said her office had been conducting an open and active homicide investigation in the case since 2011, and that local and state police investigators were involved. She declined to comment on possible involvement of federal agencies.
Tsarnaev, 26, and his 19-year-old brother Dzhokhar are suspected of setting off two pressure-cooker bombs at the marathon finish line. Dzhokhar is being held at a prison hospital west of Boston awaiting trial on charges that carry the possibility of the death penalty.
'THEY JUST KNEW EACH OTHER'
Todashev knew Tsarnaev because both were mixed martial-arts fighters in Boston but had no connection to the bombing, according to friend of Todashev, identified by local media as Khusen Taramov.
Todashev had been questioned several times by law enforcement agents since the day the Tsarnaev brothers were identified as suspects in the Boston bombing, he told Central Florida News 13.
"After they found out the bombers were Chechnyans ... they started following us, watching us," said Taramov.
Todashev met with FBI agents he said, adding that the dead man had been planning to fly back to Chechnya.
Law enforcement officials have also interviewed another person of Chechen origin, ex-rebel Musa Khadzhimuratov, at his home in New Hampshire, the New York Times reported last week.
Khadzhimuratov, who had served as a bodyguard to a top Chechen separatist leader during the region's civil war with Russia more than a decade ago, also had contact with Tsarnaev.
Neighbours said that in recent weeks, they had noticed what looked like undercover officers in unmarked cars in the parking lot outside the apartment complex where Todashev was shot and killed.
Several neighbours said he jogged on the paths through the complex shadow boxing, and sometimes swam laps in the pool and sparred with friends on the pool deck.
Todashev was arrested on May 4 and charged with aggravated battery after getting into a fight with another man over a parking space at an Orlando shopping mall, according to the Orange County Sheriff's Office in Orlando.
The man, who suffered a split upper lip and had several teeth knocked out of place, did not to press charges against Todashev, who was released from jail on a US$3,500 bond, a sheriff's spokeswoman said.
Before the Boston bombings, Tamerlan Tsarnaev had been listed on multiple US government databases, including a master list of potential terrorism suspects.
US authorities also were asked twice by Russia to investigate Tsarnaev for possible involvement with Islamic militants.