Another snip from “History Will Prove Us Right” by Howard Willens, page 42-42:
The commission had a long discussion about the FBI report and its annexes, which the members had received a week earlier. Warren and Russell noted that virtually everything contained in the FBI report had already appeared in the press. One major issue that came up right away was the bureau’s preliminary finding regarding the bullets that struck President Kennedy and wounded Governor Connally. The FBI concluded that two bullets had struck the president and a third had wounded Connally. To support this assessment, the FBI relied in part on the initial, but inaccurate, information from Parkland Hospital that the first bullet that hit Kennedy had not exited from his body. As captured in the transcript of the meeting, the members did not react favorably. BOGGS: “There is nothing in there about Governor Connally.” CHAIRMAN: “No.” COOPER: “ And whether or not they found any bullets in him.” MCCLOY: “This bullet business leaves me confused.” CHAIRMAN: “It’s totally inconclusive.” […] MCCLOY: “I think you ought to have the autopsy documents.” CHAIRMAN: “By all means we ought to have the medical reports.” McCloy reminded members that the FBI had been under considerable pressure to complete the report.42 Warren proposed that the commission request all agencies submitting reports to provide the underlying investigative materials on which they were based. He told the members that after reading the FBI report he had the feeling that “unless we had the raw materials that went into the making of this report and had an opportunity to examine those raw materials and make our own appraisal, that any appraisal of this report would be little or nothing.” He added that the commission should continue to get such raw materials as they are obtained from the agencies so that it could be kept current regarding ongoing investigations. The commission unanimously approved his motion and followed this practice with respect to all the summary reports submitted by the FBI, CIA, and Secret Service. By emphasizing its need to see the basic investigative materials—the interview reports, the ballistic and other scientific analyses, and key documents—the commission was driving home the message that it alone had the responsibility to evaluate all the evidence and reach its own conclusions.43
This is not, I repeat not, depending solely on the FBI for their information.