The United States House Select Committee on Assassinations withheld information from the Warren Commission publication. This caused a big loss in trust in the government and the conclusions they found in the investigation. Chief Justice Earl Warren was friends with the Kennedy family prior to JFK's assassination, but that information was never disclosed in the commission report. Warren could have let his emotional ties to the investigation skew the results. During one portion of the investigation, he forbade everyone else on the committee to look at the autopsy photos because they were too gruesome. The Warren Commission was also never able to conclude why Oswald killed Kennedy. The reports cite that his violent tendencies are why he committed the assassination. Since the government isn't able to say why JFK was assassinated, it is difficult for citizens to trust their conclusions from the investigation.
The information withheld from the Warren Commission report was not important to the investigation. Even though Chief Warren knew the Kennedy family prior to the assassination, it would not affect his ability to conduct an investigation. Additionally, the U.S. government was not able to conclude why Kennedy was assassinated because Jack Ruby assassinated Oswald, something that was out of their control. If it weren't for Ruby, Oswald might have revealed his motives for the assassination.
[P1] There was information withheld from the Warren Commission report. [P2] Chief Warren had a close friendship with the Kennedy family prior to the assassination. [P3] The Warren Commission report was unable to conclude why Lee Harvey Oswald assassinated JFK. [P4] Therefore, U.S. citizens lost trust in the government.
Rejecting the premises
[Rejecting P1] The information that was withheld was not important to the investigation.