What did Gerald Ford know about Nixon's crimes?

Gerald Ford, who was selected as Vice President Agnew's successor after Agnew resigned for corruption, knew by August 5, 1974, as did the rest of the country, that Nixon had illegally attempted to block the FBI investigation into the break-in of Democratic National Party headquarters at the Watergate Hotel. The release of White House recordings established that beyond any doubt. By the time Ford was sworn into office as president later that month, he was fully aware that Nixon was a criminal. Nevertheless, Ford granted him a full pardon in September of 1974.
That Ford felt some guilt over this act is attested to from the fact that he carried in his wallet a copy of a court decision that said that a pardon implied that the person pardoned was guilty. Some reports says that Ford had asked Nixon to make a public declaration of contrition in return for his pardon.
Ford's pardon was extremely unpopular at a time when many Americans believed Nixon should be punished for his crimes. The country was also still highly heated over the Vietnam war, which was still ongoing, and negative feelings against Nixon ran very high. Many historians believe the pardon so badly undermined Ford's credibility that it cost him the election in 1976. Many citizens at the time believed there had been "deal" for Ford to become president in return for a full pardon. Nevertheless, the pardon did help calm the country down.