"On the basis of the evidence reviewed in this chapter, the Commission has found that Lee Harvey Oswald (1) owned and possessed the rifle used to kill President Kennedy and wound Governor Connally, (2) brought this rifle into the Depository Building on the morning of the assassination, (3) was present, at the time of the assassination, at the window from which the shots were fired (4) killed Dallas Police Officer J. D. Tippit in an apparent attempt to escape, (5) resisted arrest by drawing a fully loaded pistol and attempting to shoot another police officer, (6) lied to the police after his arrest concerning important substantive matters, (7) attempted, in April 1963, to kill Maj. Gen. Edwin A. Walker, and (8) possessed the capability with a rifle which would have enabled him to commit the assassination. On the basis of these findings the Commission has concluded that Lee Harvey Oswald was the assassin of President Kennedy." 
- Warren Commission
Lee Harvey Oswald was 24 when he was identified by the Warren Commision to have killed President John Fitzgerald Kennedy. No motive was ever found.

Oswald, born October 18, 1939, had served in the Marine Corps from 1956 to 1959, where he is to have gained classified knowledge of secret missions pertaining to U-2 planes (He was also reportedly given LSD at Atsugi Air Base). Oswald defected and went to live in the USSR in Minsk until 1962, and he met his wife Marina during this period. It is possible that his defection was actually a lure and that there was really a CIA operation to detract attention from. There is evidence that Oswald had relations to both the CIA, FBI, and also ONI. This has not been confirmed, though.

He returned to America with his family in 1962 and lived shortly in Fort Worth, Texas before moving to Dallas where he worked at the graphic arts company Jaggers-Chiles-Stovall. Oswald left Marina in Dallas in the summer of 1963 and went to New Orleans to live with some relatives while working at the William Reily Coffee Company. It was in New Orleans that he became related to anti-Castro Cubans and Americans, even though he was arrested for distributing pro-Castro propaganda for the Fair Play for Cuba Committee. He had established a fake branch of the committee at 544 Camp Street/531 Lafayette Street (where a Guy Banister had his offices) in N.O.

In the early fall of 1963, Oswald returned to Dallas and continued to live (in rented rooms) seperated from Marina, who stayed along with Oswald's two daughters in the home of Ruth Paine in Irving, a suburb to Dallas. The Warren Commision states that Oswald made a trip to Mexico City to visit the Soviet and Cuban embassies there, possibly to arrange passage back to Russia. Some researchers do not think this is true.

On November 8, 1963, Oswald took a job as a warehouseman at the Texas School Book Repository building. Two weeks later, on November 22, 1963, Oswald allegedly fired 3 shots against the presidential parade, killing President Kennedy.

40 minutes after the assassination, Lee Harvey Oswald was arrested in the a theater in Oak Cliff for the killing of Police Officer J. D. Tippit (Oswald allegedly shot him while trying to escape the scene of crime). Upon his arrest, Oswald is said to have yelled "I am not resisting arrest", and at a press conference, he said "I'm just a patsy" as he was being led out, a word that is still associated with him when the question of his guilt repeatedly resurfaces.

Lee Harvey Oswald was shot by nightclub owner Jack Ruby in the garage of the Dallas Police headquarters on November 24, 1963 and the murder was shown live on TV.

Thanks go to JerboaKolinowski for extra input.