Jason Bourne is a fictitious assassin for the CIA.
Years ago, David Webb lived an idealic life as a young foreign service officer in Phnom Penh. Being fluent in several languages of the Orient, he was an 'up-and-comer' in the area. Married to a young woman from Thailand, father of two children, happy in his work and homelife, David Webb was happy.
It was all destroyed when, during the beginning of the Vietnam war, a stray aircraft made a devastating strafing run along the riverbank the Webbs called home. The wife and the children were riddled with bullets before Webb's eyes and he was left to bury his life and wonder why.
Fleeing the area, Webb was beyond reason as he sought a reason for the deaths of his family. In Saigon seeking answers, he encountered Alexander Conkin who saw an opportunity to make use of Webb's abilities and his anger. After a time, Webb was introduced into the highly secret organization known as Medusa. His designation was Delta.
Years of assassination and covert operations made Webb the perfect man to choose for the role of Jason Bourne.
As shown below, a made-for-tv movie was produced in 1988 that follows the storyline fairly well. In 2002, a new version was made of the Bourne story which radically veered from the books but was successful enough to warrant other movies extending the revised story of who Bourne is.
In this revision, Jason Bourne, formerly David Webb, is a man who wants to make a difference in the war on terror so he volunteers to take part in a special program the CIA has devised. Extreme training and chemical enhancements are used to turn the agents into incredible fighting machines. They are placed in major cities around the world to await calls for duty, usually to kill enemies of the state.
Bourne is given an assignment to kill an African head of state aboard his yacht but when he has the chance, he refuses to pull the trigger since the target's children were in view. For his mercy, he is shot by the man's bodyguards and falls into the ocean to die. When he survives, he cannot remember who he is but soon learns that the Agency now totally distrusts him and wants to eliminate him to protect the secrecy of the program. Bourne may not remember who he is but he definitely remembers how to survive.