BOSTON — A friend of Boston Marathon bombing suspect Dzhokhar Tsarnaev pleaded not guilty Wednesday to charges of trafficking heroin and possessing an illegal handgun connected to the April 2013 bombings.

Stephen Silva, 21, of Cambridge, appeared in federal court in Boston to waive his right to a detention hearing. He has been in custody since his July arrest. His next court date is Oct. 8.

Authorities have said they believe Silva provided Tsarnaev and his brother, Tamerlan, with the gun used to kill Massachusetts Institute of Technology police officer Sean Collier during the dramatic manhunt following the April 2013 bombings, which killed three people and injured more than 260 others.

Silva’s grand jury indictment from July does not mention the police officer’s slaying or Tsarnaev. Instead, it focuses mostly on allegations that Silva was dealing heroin in the Boston area this summer. It also states Silva received a Ruger pistol with the serial number removed in February 2013.

That gun was used to kill Collier on April 18, 2013, as the Tsarnaevs were being sought, according to two people with knowledge of the case who spoke to The Associated Press on the condition of anonymity because they weren’t authorized to discuss the investigation.

Police have said they recovered the Ruger after a shootout in which Tamerlan was killed. Dzhokhar was found later hiding in a boat in suburban backyard. He faces the possibility of the death penalty if convicted in the bombings. He has pleaded not guilty.

Silva, who attended Cambridge Rindge and Latin High School with Dzhokhar, is one of five men connected to the Tsarnaevs who have faced charges in the aftermath of the bombings.

If convicted of conspiracy to distribute heroin, Silva faces a mandatory minimum sentence of five years and a maximum sentence of 40 years, according to prosecutors. If convicted of a possession of a firearm with an obliterated serial number, he faces a maximum sentence of 5 years. Silva also faces a maximum of 20 years for six other drug-related charges.

Silva’s family and friends, including his twin brother, Steven, were in court Wednesday but declined to comment.