A man shot to death during questioning about a Boston Marathon bombing suspect would have had a difficult time attacking officers because he was still limping after major knee surgery about a week earlier, lawyers for his father said Tuesday at a news conference.

Ibragim Todashev, 27, was killed in May while FBI agents and police from Massachusetts and Florida questioned him at his Orlando apartment about his friendship with suspected Boston Marathon bomber Tamerlan Tsarnaev. Officials originally said the Chechen man lunged at an agent with a knife. They later said it was no longer clear what happened. An investigation is being led by the FBI.

Separately, in Boston on Tuesday, two college friends of the surviving Boston Marathon bombing suspect pleaded not guilty to allegations they conspired to obstruct justice by agreeing to destroy and conceal some of their friend’s belongings as he evaded authorities. Dias Kadyrbayev and Azamat Tazhayakov, who shared an apartment in New Bedford, Mass., became friends with bombing suspect Dzhokhar Tsarnaev when they all started school at the University of Massachusetts-Dartmouth in 2011. The two friends of Tsarnaev’s are from Kazakhstan.

Tsarnaev is accused of setting off two bombs near the race’s finish line that killed three and wounded hundreds April 15. He has pleaded not guilty. Authorities say he was working with his older brother, Tamerlan, who died during the manhunt for the suspects days later.

Kadyrbayev’s attorney, Robert Stahl, has said his client never knowingly took evidence from the dorm room and fully cooperated with the FBI. Tazhayakov’s lawyer, Arkady Bukh, has said his client never agreed to anything when it came to disposal of the backpack with the fireworks. He said his client hasn’t done anything wrong and he’s been trying to get authorities to drop the case.

Amir Ismagulov, the father of Azamat Tazhayakov, said after the court hearing that his 19-year-old son is “absolutely not guilty” and that the FBI made a mistake by arresting him.

Back in Florida, the lawyers for Todashev’s father, Abdulbaki Todashev, said Tuesday that a former detective they hired to investigate the shooting death told them that all the law enforcement agents in the room would have drawn their weapons and fired if they believed their lives were in danger — but based on their findings, they don’t believe that happened.

FBI spokesman Paul Bresson said he couldn’t comment on what was said at the news conference because the shooting investigation is ongoing.

But he referred to a statement that was issued by the FBI immediately after the shooting last May.

“The Special Agent, along with other law enforcement personnel, were interviewing an individual in connection with the Boston Marathon bombing investigation when a violent confrontation was initiated by the individual,” the statement said. “The Special Agent, 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 U.S. Department of Justice is investigating what happened, and State Attorney Jeff Ashton in Orlando said last week that he would review the circumstances that led to the fatal shooting.

Abdulbaki Todashev also spoke at the news conference, tearing up over his son. Abdulbaki Todashev said he came to Florida from Chechnya last week to try to learn more about what happened.

“My son was a very good boy,” Abdulbaki Todashev said through a Russian translator. “He was a good grandson to his grandparents. He was a good brother. He was a good neighbor. … He was innocent, and he was simply killed.”