Ibragim Todashev was fatally shot early May 22 during questioning about a 2011 triple homicide in Waltham, Massachusetts, as well as his relationship with deceased Boston Marathon bombings suspect Tamerlan Tsarnaev.
Todashev admitted to his direct role in slashing three people's throats in Waltham and said Tsarnaev was involved as well, a federal law enforcement official told CNN.
It was during that interview -- which took place in the kitchen of his Orlando, Florida, home -- that Todashev was shot dead.
"My son was definitely unarmed, because he never had a gun," his father Abdulbaki Todashev told CNN in Moscow. "He couldn't attack them or fight them; he couldn't do anything because even two men could easily handle him."
Contrary to what a U.S. official said, Todashev's father claimed there were "four of five" law enforcement agents with his son at the time, "all armed."
"He didn't pose any threat to them. But even if he threatened them with his fists, couldn't they shoot his leg?" Abdulbaki Todashev said. "My son couldn't attack them. He's not crazy."
Addressing reporters on Thursday, Abdulbaki Todashev added his son had recently undergone leg surgery and needed crutches to walk.
Photographs of his son's body show that he was shot seven times, once to the head, said Abdulbaki Todashev.
"They were torturing the man for eight hours. There was no lawyer, no witnesses, nobody. Until we get the results of the official investigation, we can only guess what was going on there."
The elder Todashev suggested his son may have been provoked. "If you question someone for eight hours, you can provoke him into anything," he said.
The father said he had spent much of his life raising his 12 children, and that he knew Ibragim well. "I know what he is capable and not capable of. My son could not have done this."
A U.S. government official briefed on the investigation said Thursday that Todashev had agreed to talk to authorities,and noted that he was never arrested or handcuffed.
A samurai sword was in the room when Todashev sat down with two Massachusetts State Police detectives and a Boston-based FBI agent, but it was moved out of his reach.
After one of the detectives left the room, the other noticed Todashev was acting odd and he texted that sense to the FBI agent with him -- the U.S. official told CNN. Those two law enforcement officials were the only ones with Todashev, according to this account.
Suddenly, Todashev knocked over a table -- knocking the FBI agent back into a wall -- and came at him with some sort of "long-handled object" that he'd grabbed from behind him, according to the official.
The agent fired a few rounds, but Todashev kept on coming, the official said. He finally stopped after yet more gunshots.
"It all happened in less than a minute," said the U.S. official.
A law enforcement official told CNN on Friday that Todashev attacked the FBI agent with a broom handle, not a sword. "He (Todashev) took a whack at his (the agent's) head, and he got a pretty good gash."
The official said that investigators knew going into the questioning that Todashev was proficient in mixed martial arts.
The official stressed that the shooting was justified and done in self-defense because the agent felt threatened.
The description of what allegedly happened -- as well as the comments from the elder Todashev -- come a day after CNN affiliate WESH and the Washington Post, citing unidentified sources, reported Todashev was unarmed when he was shot.
That led the Florida chapter of the Council on American-Islamic Relations to call Wednesday for an investigation into the death of the Muslim man.
"Our call for an independent investigation of this disturbing incident is not just about the victim and his family, but is also about constitutional rights and the rule of law," said CAIR-Tampa Executive Director Hassan Shibly.
But the U.S. government official briefed on the investigation rebuffed the idea that Todashev wasn't a threat -- noting, for instance, that he could have taken the agent's gun.
"He was armed. Maybe it wasn't a weapon, but he had a long object," the official said. And because of Todashev's martial arts expertise, "he was a weapon himself."
An FBI spokesman earlier said the agent sustained "non-life-threatening injuries" in the incident. The U.S. official elaborated that the agent received treatment for lacerations.
Abdulbaki Todashev said he planned to fly "hopefully" Friday to the United States to bring "my son's body back to his homeland and bury him here."
"(He was) a regular, funny boy (who) loved his brothers and sisters," the father said. "He wanted to stay (in the United States and I) said it was a nice place to train and to live. I said he should stay there."
The FBI opened an investigation into the incident after the killing -- standard procedure in any shooting that involves an agent.
"While this internal review process is occurring, we cannot comment regarding investigative details," FBI spokesman Paul Bresson said Wednesday.
"The FBI takes very seriously any shooting incidents involving our agents and as such we have an effective, time-tested process for addressing them internally. The review process is thorough and objective and conducted as expeditiously as possible under the circumstances."
Todashev and Tsarnaev had become acquainted at a mixed martial arts center near Boston, said a source who was briefed on the bombing investigation.
Todashev had Tsarnaev's phone number in his cell phone, the source said.
Todashev was from the Chechnya region, as were Tamerlan and Dzhokar Tsarnaev, the source said. Dzhokhar, Tamerlan's brother, is a suspect in the April bombings in Boston.
Abdulbaki Todashev doesn't believe his son admitted to any involvement in the Waltham triple homicide, saying "the FBI can say anything now because a dead person can't defend himself."
That said, the father said he believes "there are lots of honest workers" in U.S. law enforcement who he thinks "can be trusted (to) conduct a fair investigation" into his son's death.
"I do want justice," Abdulbaki Todashev told CNN. "I've always taught my children about justice. I do believe in it."