The FBI's dossier on Chávez was obtained under the Freedom of Information Act (FOIA), which contains provisions that allowed the FBI to withhold portions of the documents from public view. Indeed, many parts—and in some cases, entire pages—have been excised from the files. Nevertheless, the collection provides a compelling window into the efforts of the farmworker movement, as well as the values and methods of the FBI itself.
As part of its investigation of the farm labor movement, the Federal Bureau of Investigation's (FBI) field office in Los Angeles circulated information on U.S. Senate subcommittee hearings and a National Farm Workers Association (NFWA) protest march in March 1966. Since 1965, the Delano grape strike had drawn national attention to the poor working conditions and low wages of farm laborers. As a result, the federal Subcommittee on Migratory Labor held hearings in Sacramento, Visalia, and Delano from March 14-16; Sen. Robert F. Kennedy's participation in the hearings led to his high-profile advocacy for migrant workers. On March 17, César Chávez began a 300-mile march from Delano to Sacramento, which rallied thousands of supporters and generated publicity for the rights of farm workers.
According to documents dated on March 3 and March 10, individuals involved in the subcommittee hearings had asked the FBI to provide in provide information on the farm workers movement. On March 9, the Los Angeles field office noted separate investigations into the strikes by the California State Senate Fact Finding Committee of Un-American Activities and the U.S. Subcommittee on Migratory Farm Labor. The memo also noted tension between the NFWA and the United Auto Workers (UAW) over funds.
According to a March 14 communiqué, the Los Angeles field office reported that a source had received information from the NFWA regarding the details of their planned march to Sacramento—including the itinerary, the number of participants, and logistical arrangements—which were passed to law enforcement agencies. Subsequent documents discussed planning sessions for the march involving the Congress of Racial Equality (CORE), the Student Nonviolent Coordinating Committee (SNCC), and the Southern California District Communist Party.