SPRINGFIELD, Mass. (AP) – A drug trafficker tied to the slaying of reputed mob boss Adolfo “Big Al” Bruno pleaded not guilty to a murder charge Tuesday.

Brandon Croteau, who is already serving a 15-year prison sentence for selling cocaine, is the third person charged in the 2003 killing of Bruno, who authorities said was the local chief of the New York-based Genovese crime family.

Prosecutors say Frankie Roche was the triggerman, and was helped by Croteau and Fotios Geas.

Geas and Roche already have pleaded not guilty to murdering Bruno and currently are being held without bail.

Authorities have not offered a motive for Bruno’s murder.