John Deluca was a Gunnery Sergeant in the United States Marine Corps and also also the head of his own team at the Army CID.
NCIS Season 1Edit
His first appearance was in The Curse (episode).
NCIS Season 2Edit
His second and final appearance to date in The Bone Yard (episode) where he clashed with Special Agent Leroy Jethro Gibbs over the death of a civilian at a bombing range although it was later revealed that the civilian was an undercover agent working for the FBI and that his death was connected to the local mob.