On June 5, 1968, United States Senator Robert F. Kennedy was shot and killed in the kitchen of the Ambassador Hotel in Los Angeles, California. Kennedy had just won the California primary election for the Democratic nomination for President earlier that night. While Kennedy was passing through the hotel's kitchen, Sirhan Bishara Sirhan, a 24-year old Palestinian immigrant, shot and killed the presidential hopeful. Sirhan subsequently confessed to the crime, was convicted of first-degree murder on April 17, 1969, and is currently serving a life sentence for Kennedy's assassination.

Despite Sirhan's confession and conviction, many believed that Kennedy's assassination was not so cut and dry. Gregory Freeman Stone, a former political science doctoral candidate at the University of Wisconsin, was one such individual. From his research, Stone came to believe that Sirhan did not act alone but was assisted by a second gunman, who was responsible for firing the bullet that ultimately killed the Senator. Stone devoted his life to searching for evidence to support this theory.

In 1985, Stone dropped out of his doctoral studies program in order to spend more time on the case. He subsequently moved to Los Angeles to continue his research and the small duplex in which he lived served as the main location for his collection of materials related to the assassination. In 1988, the Los Angeles Police Department released their files regarding the investigation and credit Stone as being instrumental in making this happen. These files are currently housed in the California State Archives.

Stone and his colleagues were confident that their research would finally launch a reinvestigation into the murder. On May 13, 1990, the Washington Post published an article by Dan Moldea in which the author stated that more bullets were fired than could be accounted for in Sirhan's revolver, nine to twelve in total. Stone's research was vital to Moldea's conclusion. The following week Stone and his colleagues held a press conference to present their findings on the second gunman. The findings received national attention but did not lead to the reinvestigation into the murder the group hoped for. Stone was deeply upset by the outcome and developed depression. In 1991, he committed suicide.