first time while both waiting for a train. Gibbs was leaving for Marine Combat Training having just graduated from bootcamp. At that first meeting, Shannon mentioned she had thought about creating a set of life rules for herself; Gibbs later incorporated this idea into his own series of around fifty rules that he now lives by (with the rules in the forties and above supposedly used for emergency situations). Gibbs is known by his first name, Leroy, to family and people in his hometown (as well as his ex-wife Diane), whereas at work he is known as Gibbs, Jethro, or simply "Boss". Shannon called him both Gibbs and Jethro. Gibbs' mother, Ann, is introduced in "Life Before His Eyes", the 200th episode. She was a redhead, like all of Gibbs' wives. While she was dying of cancer, she took her own life by overdose so her family would not have to watch her suffer ("The Namesake"). Gibbs enlisted in the Marine Corps in 1976 and was a military police non-commissioned officer at Camp Lejeune before becoming a Scout Sniper. After graduating from bootcamp, Gibbs shipped out to Camp LeJeune for further training. There he befriended fellow Marine Private First Class Joan Matteson, but she was one of several marines killed in a helicopter crash on 03 April 1977 after she was deployed to Okinawa, Japan. He served on tours of duty in Panama (Operation Just Cause) and with the 1st Battalion 1st Marines in the Persian Gulf (Operation Desert Storm). In the season 6 episode "Deliverance", it is revealed that he was also deployed to Colombia on a classified mission. Not long after returning from the Gulf, he retired from the Marine Corps with the rank of Gunnery Sergeant and joined the Naval Investigative Service (as the Naval Criminal Investigative Service was then called) in August 1992. As a junior agent, Gibbs was mentored by Mike Franks, and the two became close friends; Franks continued calling him "Probie" even after retirement. After Franks retired, Gibbs rose to become head of his own Major Case Response Team. Before the time in which NCIS is set, Gibbs was described to have traveled extensively on operations, particularly in Eastern Europe. Gibbs is a highly skilled marksman with both his agency-issued SIG Sauer P228 pistol (which he replaces with a .45 Colt M1911A1 pistol in Season 15) and a sniper rifle. In the season