>>> there has been a new development in the boston marathon bombing investigation which led to a deadly confrontation between a man who knew the alleged bombers and law enforcement . our justice correspondent pete williams covering this all day has more from our d.c. newsroom tonight. pete, good evening.

>> reporter: brian, investigators say their search for friends of bombing suspect tamerlan tsarnaev took them to florida to question ibragim todashev, a native of russia and a mixed martial arts fighter. while being interrogated last night at a house in orlando, officials say he attacked an fbi agent and was shot and killed. authorities say before that todashev confessed to playing a role in a brutal murder in massachusetts in 2011 . one of the victims was a friend of tsarnaev's. todashev said tsarnaev was involved in the killing, too. todashev lived for a time in the boston suburb and became friends with tsarnaev who was a boxer there. they say the killings started as an attempt to steal drugs from the three victims but ended in their deaths to keep them from talking. authorities say they do not believe todashev had any role in the boston marathon bombings, brian.

>> pete williams in our d.c. newsroom. pete, thanks.