At the time of the August 29, 1970, National Moratorium March, Ruben Salazar was a highly respected columnist for the Los Angeles Times and news director for KMEX-TV, Los Angeles' first Spanish language station. In 1959 he had joined the Los Angeles Times as a reporter, becoming the first Latino journalist in the US to work for an elite mainstream newspaper. In 1963 he wrote an award-winning series on "Spanish-speaking Angelenos," addressing much needed educational reforms and other civil rights injustices in the Mexican American community. From 1965 to 1968, Salazar was assigned to the L.A. Times' foreign desk, he spent time in Vietnam covering the war, and held the coveted position of L.A. Times' Mexico City Bureau Chief, covering many Latin America countries. In June 1968, the L.A, Times called him back unexpectedly to Los Angeles to cover what they saw as a "new Mexican-American uproar..." at home. (Letter from the Times foreign editor Bob Gibson to Salazar, June 13, 1968, in the Ruben Salazar papers) During that year there were many high school student walkouts, or "blowouts," in East Los Angeles. The L.A.Times possibly viewed Salazar as the journalist on their staff who could best cover these events. He and his family soon returned to California. On the day of his death he was covering the Moratorium march for the Times and for KMEX-TV. During the afternoon he and a Times photographer, one of the key witnesses, took a break from the chaos in the street and entered the Silver Dollar bar. There are still many unanswered questions about the events that day that may never be resolved. What is known for certain is that Salazar was killed instantly when he was struck by a tear gas projectile fired into the café by Deputy Thomas Wilson. As the Office of Independent Review concludes in their report "It was not an era of openness and public transparency. The Sheriff's Department … offered few explanations and no apologies. That posture fueled the skeptics." (OIR Review, p. 17)

The Los Angeles County Sheriff's Department's Records on the Investigation of the Homicide of Ruben Salazar contain historical documents dealing with the homicide investigation of the circumstances of journalist Ruben Salazar's death and extensive materials about the National Chicano Moratorium March, among the largest anti-Vietnam War protests in Los Angeles, held on August 29, 1970. Included are documents on the planning and events leading up to that day, information on the organizers, intelligence on radical groups and participants of the march, and the tragic conclusion. By the end of the day, the march that began peacefully at Belvedere Park in East Los Angeles had become a full-blown riot near Laguna Park, with extensive damages, many arrests, complaint reports, and three deaths, including Salazar’s at the Silver Dollar bar. Following the homicide investigation, there was a 16-day televised Coroner's inquest, one of the longest and most costly in Los Angeles' history. When it concluded, District Attorney Evelle Younger issued a statement indicating among other things that he would not pursue criminal charges against Deputy Wilson, who had fired the tear gas projectile that killed Salazar. Sheriff Peter Pitchess followed with a statement indicating there had been no misconduct by any of the deputies involved in the shooting or during the riot. Salazar’s wife Sally filed a wrongful death lawsuit against the County of Los Angeles and was awarded damages. The case was considered closed and the files were inaccessible for forty years. In 2011 the Los Angeles County Office of Independent Review (OIR), at the request of the Los Angeles County Sheriff, produced a special report after a careful examination of the files. The OIR's Review, many Public Record Acts requests for access in 2010, on the fortieth anniversary of Salazar’s death, media coverage, and a lawsuit by MALDEF, eventually led to the opening of the files.

From 1965 to 1970 there had been an increasing number of Vietnam War protests in many U.S cities, especially on college and university campuses. As the war continued new groups joined the antiwar movement including women, veterans, African Americans, and Chicanos. The National Chicano Moratorium was organized by the Chicano Moratorium Committee and the Congress for Mexican American Unity, a group of Chicano activists. It was unique because it was among the few ethnic antiwar movements in the U.S --part of the newly evolving Chicano movement as well as the anti-Vietnam War movement. The main concern of the Chicano Moratorium organizers was the disproportionate number of Chicanos and other Latinos or Hispanics who were being drafted and killed in Vietnam. They promoted antiwar demonstrations by Chicanos in California, the Southwest and other parts of the United States from November, 1969 to August, 1971.

1970 marked a high point of Chicano discontent with the U.S. involvement in the Vietnam War. As the files indicate, in the months leading up to the East Los Angeles National Moratorium march on August 29, there were numerous Chicano antiwar marches, rallies and student protests in California. Only a week before the August 29th march in East Los Angeles, Chicanos had marched in protest in many cities throughout the U.S. Within this context, it is not surprising that the march in East Los Angeles on August 29th attracted, as the L.A. Times reported, an estimated 20,000 demonstrators. In 1980, Times columnist Frank del Olmo, on the tenth anniversary of Salazar’s death, claimed it was the "largest Mexican American demonstration ever held in this country." As documents in the collection show, attendance at previous Chicano marches numbered one or two thousand at most, and had been conducted peacefully, without major incidents. The Los Angeles County Sheriff's Department based their preparations on previous experience and predicted in a report that this march would be similar to previous marches.