The father of the Chechen man who was fatally shot by an FBI agent last week said agents questioned his son for hours on end about one of the suspects in the Boston Marathon bombing and then killed him to keep him quiet.

Abdulbaki Todashev, who applied Thursday for a U.S. visa so that he could pick up his son’s body in Orlando, where he died, said he has heard nothing from U.S. officials about the May 22 shooting.

“I want justice. I want an investigation,” he said at a Moscow news conference. “They come to your house like bandits, and they shoot you.”

Ibragim Todashev, 27, was an acquaintance of Tamerlan Tsarnaev, the alleged planner of the Boston bombing. Todashev had moved to Florida from Massachusetts two years ago, his father said. He said FBI officials questioned his son on three occasions this spring.

The first time, the father said, they asked him about the bombing. The second time, the father said, they asked him about a triple murder in Waltham, Mass., that police suspect Tsarnaev may have carried out. The third interview, which took place at Todashev’s home and included Massachusetts state troopers, ended with his death, the father said.

Although earlier accounts of the incident suggested that Todashev had a weapon, two law enforcement officials told The Washington Post on Wednesday that he was not armed. His father said his son was shot seven times. The FBI has said that Todashev attacked an agent, just moments after confessing to his part in the Waltham slayings.

On Thursday, the medical examiner’s office in Orange County, Fla., referred all calls to the FBI. The bureau has said that an FBI review team is investigating the matter and may not conclude its probe for several months.

The elder Todashev displayed photographs of his son’s body — apparently the same pictures as those shown by participants in a Florida news conference Wednesday evening — that he said show six shots to the body and a “control” shot to the back of the head.

“This is proof of coldblooded murder,” said Maxim Shevchenko, a journalist and member of Russia’s presidential human rights council who organized Thursday’s news conference.

It was an “extrajudicial execution,” said Zaurbek Sadakhanov, a Chechen lawyer who was present. “Why was he interrogated three times without a lawyer? Why no recording? Why seven shots? And why should I believe their version? Why do American policemen believe they can do whatever they want?”

Todashev’s father said his son had been planning to return to Chechnya last Friday, though he had apparently canceled his tickets before he was killed. The father suggested that the FBI didn’t want his son to return to Russia.

“Maybe my son knew some sort of information that the police didn’t want to get out,” he said. “They shut him up. That’s my opinion.”

Abdulbaki Todashev, the father of Ibragim Todashev, shows a photo of his son's body during a news conference in Moscow, Russia, 30 May 2013. Ibragim Todashev, 27, was shot dead May 22, 2013 by FBI agents reportedly during questioning about his ties with the Boston Marathon bombing suspect Tamerlan Tsarnayev. (MAXIM SHIPENKOV/EPA)

Ibragim Todashev was the eldest of 12 children. His father said the family fled Chechnya after the wars of secession erupted there in the 1990s, eventually finding a haven in the Volga River city of Saratov. Abdulbaki Todashev had once studied to be a veterinarian there, in the Soviet era.

Ibragim Todashev studied English for three years in Saratov and then, in 2008, returned with his family to by-then more stable Chechnya and completed his fourth year of higher education at Grozny University, his father said. The elder Todashev got a job with the city. Today, he heads the administrative unit of the Grozny mayor’s office.

As soon as he left the university, Ibragim Todashev went to the United States on a program that enabled him to perfect his English, his father said. Three or four months later, when it was time to return, Todashev called his father and said he wanted to stay on a while.

“I wasn’t against it,” the father said. Chechnya was still struggling, and life in the United States had to be more secure. Ibragim was living in Boston and got to know Tsarnaev because they belonged to the same gym, his father said. They had each other’s phone numbers, he said, “but they were never close friends.”

Ibragim Todashev applied for a green card, which meant he had to stay in the United States. He stayed active in mixed martial arts, but a knee injury and surgery on his meniscus put an end to those dreams. Two months ago, his father said, he received the green card, and that’s when he started making plans to come back to Grozny for a visit, knowing he would be able to reenter the United States.

After the Boston bombing, Todashev called his father and told him that he was being watched. He said he didn’t believe that Tsarnaev and his brother, Dzhokhar, were responsible for the bombing. “This is a set-up,” he told his father. And he told him about the first two rounds of questioning by the FBI.

The elder Todashev said he learned of his son’s death when Khusen Taramov, a friend and fellow Chechen, called him. Taramov had been at Todashev’s apartment the night of May 22. The FBI called and asked Ibragim Todashev to come by for more questioning, but he told bureau officials that they could find him at home, his father said Thursday.

When they arrived, they took Taramov aside and interrogated him outdoors for several hours, the father said, then told him to go. A few hours later, the younger Todashev was shot.

Abdulbaki Todashev is convinced that his son is innocent of the Waltham killings. “I raised him. I know what kind of person he is,” he said.

Shevchenko decried the “systematic persecution of Chechens” in the United States and accused the Russian Foreign Ministry of not doing more to stand up for Chechens who are abroad.

Sadakhanov, the lawyer, said he had some advice for Taramov: Leave the country. “Nowadays, it’s not safe to be a witness in the United States,” he said.

Peter Finn in Washington contributed to this report.