Supervisory Special Agent Leroy Jethro Gibbs (Mark Harmon) was born in Stillwater, Pennsylvania to Jackson and Ann Gibbs. He enlisted in the Marine Corps in 1976 and became a Scout Sniper. After serving in Panama and Iraq, he retired from the Marine Corps with the rank of Gunnery Sergeant. He joined NIS, which later became NCIS, after his wife Shannon and only daughter Kelly were murdered in 1991. He later travelled to Mexico and murdered the drug dealer responsible, a crime he kept concealed for twenty years. Since then, he has been married and divorced three times, and is single, although he has had a number of romantic relationships since his last divorce.