Before the release of this tape, Nixon had denied any involvement in the scandal. He claimed that there were no political motivations in his instructions to the CIA, and claimed he had no knowledge before March 21, 1973, of involvement by senior campaign officials such as John Mitchell. The contents of this tape persuaded Nixon's own lawyers, Fred Buzhardt and James St. Clair, that "the President had lied to the nation, to his closest aides, and to his own lawyers—for more than two years". The tape, which Barber Conable referred to as a "smoking gun", proved that Nixon had been involved in the cover-up from the beginning.