When I moved to Texas in 1978 I hesitated for a long time to talk about JBJ and JFK. One day when we were sitting arounf and BSing I asked the native Texans if they thought LBJ was behind killing JFK and to a man they all said “Of course he was”.
The CIA would have never done it unless they were dead sure that the Veep wouldn’t unleash hell on them, especially with JFKs brother being the Attorney General.
LBJ cheated his way into office, was an exceptionally crude and vulgar man, and is reputed to have murdered in Texas before. He also suspected he might get dropped from the ticket.
It was obvious shortly afterward that JBJ had the most to gain. There was some odd things that happened aboard AF 2 that JBJ was flying in - I can no longer remember what exactly, some 60 years having gone by. There likely is some source somewhere in some library - internet sources would have been scrubbed many many decades ago.