Rockefeller Commission Report
Prior to the so-called Church Committee, the President's Commission on CIA Activities Within the United States was formed by President Gerald Ford. Headed by Vice-President Nelson Rockefeller, this body came to be known as the Rockefeller Commission.
The Rockefeller Commission issued a single report in 1975, which delineated some CIA abuses including mail opening and surveillance of domestic dissident groups. It also conducted a narrow study of issues relating to the JFK assassination, specifically the backward head snap as seen in the Zapruder film (first shown publicly in 1975), and the possible presence of E. Howard Hunt and Frank Sturgis in Dallas.
The Rockefeller Report is seen by many as a "whitewash," and was certainly superceded by the Church Committee's work in scope and depth.
The files of the Rockefeller Commission were reviewed by the Church Committee, and many of them are included as part of the roughly 50,000 pages of declassified Church Committee documents now publicly available at the National Archives.
https://www.intelligence.senate.gov/sites/default/files/94755_III.pdf