The story accounts for two trips to Las Vegas, Nevada, that Hunter S. Thompson and attorney Oscar Zeta Acosta took in March and April 1971. The first trip spawned from an exposé Thompson was writing for "Rolling Stone" magazine about the Mexican-American television journalist Ruben Salazar, whom officers of the Los Angeles County Sheriff's Office had shot and killed with a tear gas grenade fired at close range during the National Chicano Moratorium March against the Vietnam War in 1970. Thompson was using Acosta — a prominent Mexican-American political activist and attorney — as a central source for the story, and the two found it difficult for a brown-skinned Mexican to talk openly with a white reporter in the racially tense atmosphere of Los Angeles, California. The two needed a more comfortable place to discuss the story and decided to take advantage of a "Sports Illustrated" magazine offer to write photograph captions for the annual Mint 400 desert race being held in Las Vegas.