A friend of Boston Marathon bombing suspect Dzhokhar Tsarnaev has pleaded not guilty to charges of trafficking heroin and possessing an illegal handgun.
Stephen Silva of Cambridge, Mass., appeared in federal court in Boston on Wednesday.
Authorities believe Silva provided Tsarnaev and his brother, Tamerlan Tsarnaev, with the handgun used to kill Massachusetts Institute of Technology police officer Sean Collier during the manhunt following last year's bombing.
Tamerlan Tsarnaev was killed in a shootout with police several days after the bombings.
Dzhokhar Tsarnaev was found later hiding in a boat. He has pleaded not guilty in the bombings.
An indictment also alleges Silva conspired to distribute heroin. He waived his right to a bail hearing Wednesday and remains in custody.
