(Adds reaction from Muslim civil liberties group, details)
By David Ingram and Barbara Liston
WASHINGTON/ORLANDO, Fla., March 21 (Reuters) - Investigators have concluded that an FBI agent should be cleared of any wrongdoing in the fatal shooting of a Chechen immigrant while he was being questioned about his ties to one of the Boston Marathon bombing suspects, a federal law enforcement official said on Friday.
The agent shot and killed 27-year-old Ibragim Todashev in May 2013 after Todashev suddenly attacked and injured the agent during an interrogation at his Orlando apartment, according to the FBI.
The law enforcement official spoke on condition of anonymity ahead of the release on Tuesday of a review of the incident by a Florida prosecutor.
The report prepared by a team of investigators at the office of Orlando State Attorney, Jeffrey Ashton, recommends clearing the FBI agent, the official said. A separate unpublished FBI report, has also concluded the agent was justified in using deadly force, the official said.
A statement issued by Ashton's office on Friday said no "final decision" had been made in his investigation and that he was expected to review the findings over the weekend.
Todashev was an acquaintance of Tamerlan Tsarnaev, one of two Chechen brothers who prosecutors say carried out the Boston bombings that killed three people and injured more than 260.
He was shot and killed while being questioned about his suspected involvement in a triple murder in 2011 that law enforcement officials suspected was linked to him and Tsarnaev.
The FBI account has been questioned by Todashev's father, who has said his son was unarmed when he was shot. A Muslim civil liberties group in Florida, the Tampa-based branch of the Council on American-Islamic Relations, has called for a detailed review of the shooting.
U.S. prosecutors could announce their decision not to bring charges against the FBI agent as soon as Tuesday, the same day Ashton is expected to announce the findings of his investigation, said the official.
Hassan Shibly, executive director of the Florida Council on American-Islamic Relations, expressed concern about the conclusions of the investigations.
"The Department of Justice's and the State Attorney's investigations relied on evidence gathered by the FBI and the only person who can contradict first hand their narrative is dead," Shibly said in a statement.
He also said his group has been complaining to U.S. officials about what they call a pattern of mistreatment of Todashev's friends after the shooting.
The group said U.S. immigration officials were refusing to allow a friend of Todashev, Khusen Taramov, and his two brothers to return to the United States from Russia.
Taramov told Reuters after the shooting that he had accompanied Todashev to his apartment before the FBI interview on the night he was killed.
Taramov and his brothers are all permanent U.S. residents, according to Shibly, and traveled to Russia after the shooting to visit family.
Another Todashev friend, Tatiana Gruzdeva, was deported after being questioned by immigration officers and FBI agents, Shiby said.
Shibly said his group hired a homicide investigator to conduct an independent review of Todashev's killing last year.
The investigator concluded that Todashev was shot seven times and received a major wound, possibly a bullet, to the back of the head.
He also found blood splatter and other physical damage at the scene which pointed to Todashev being shot while he was lying on the ground, Shibly said.
The FBI has yet to release the autopsy report which could help confirm the details of the shooting. (Writing by Kevin Gray; Editing by Chizu Nomiyama, Chris Reese and Tom Brown)