Several of Todashev's former roommates who were questioned by the FBI said he knew Tamerlan Tsarnaev, an aspiring boxer, from mixed martial arts fighting in Boston and that the FBI was asking about him.
Muslin Chapkhanov, a former roommate, said Todashev "was living in Boston and I think he trained with" Tamerlan Tsarnaev.
Tsarnaev's younger brother, Dzhokhar, survived the shootout with police and is now charged with carrying out the attack that killed three people and wounded more than 260 in downtown Boston. He is also charged in the slaying of an MIT police officer days later.
Todashev's father said his son gave up martial arts because of an injury and later held a number of jobs, including as a driver at a retirement home, before moving to Florida within the past year. Todashev had lived on and off with other Chechens in the Orlando suburb of Kissimmee and had moved to Orlando more recently, friends said.
His father said his son had planned to come to Chechnya this week to visit his extended family, but was asked by the FBI to delay his trip.
Investigators have been trying to establish the scope of the plot. In addition, authorities in Massachusetts said they would investigate whether Tamerlan Tsarnaev had any connection to the unsolved 2011 deaths in the Boston suburb of Waltham, where three men were found in an apartment, their throats slit and marijuana sprinkled over their bodies. One of the victims was a boxer and a friend of Tsarnaev's.
While he was being interviewed, Todashev made statements implicating himself in the 2011 Waltham slayings, two officials briefed on the investigation said. Neither official knew whether Todashev had also implicated Tamerlan Tsarnaev in the killings. The two, a federal law enforcement official and a Massachusetts state official, spoke on condition of anonymity because they were not authorized to release details of the investigation.