It was published in the 'Washington Star' in June of 1976. The comment was accidentally made to Smith at the start of an interview with LBJ back in 1963. He immediately realised he had said something he wasn't supposed to talk about yet, and refused to acknowledge any of the very stunned Smith's questions about what he had just let slip. Smith told a handfull of people, one being Jack Anderson who would later break the "Murder INC." story about the Kennedys trying to get Castro whacked.
I have read that LBJ killed JFK so if he said that he was trying to deflect blame from himself.
Maybe that writer is the one who killed JFK and is only trying to deflect blame onto LBJ...