The primary source document described below, which can be viewed by clicking the thumbnail at right, is part of a 1,434-page file on César Chávez and the farmworker movement compiled by the Federal Bureau of Investigation (FBI) between 1965 and 1973. The FBI's surveillance of Chávez, which paralleled larger efforts to prove that protest groups of the civil rights era had been infiltrated by subversive influences, was unable to uncover any evidence of communism or corruption in the activities of Chávez and his followers.

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.

In a memo dated January 31, 1973, U.S. Assistant Attorney General Henry E. Petersen requests the FBI to investigate an attack against United Farm Workers (UFW) offices in Tulare County, California. Peterson indicated that the incident could be a violation of Title 29 Section 530 of the U.S. Code, which prohibits the deprivation of union organizing rights through the use of violence, and Title 18 Section 241, which provides provisions against conspiracies to deny citizens of their constitutional rights.

Petersen writes that on January 29, Chávez sent his office a telegram regarding attacks on several UFW offices in Tulare County. Specifically, Chávez alleged, the organization's offices in Delano were set with explosives during the week of January 22; its Terra Bella office was destroyed on January 28; and its Poplar office was also attacked. Further, union members had been threatened with physical harm.

A subsequent document dated February 1 shows the FBI directing its Sacramento field office to conduct an investigation regarding the incident.