Want a great read on this topic? Try reading LBJ: The Mastermind of the JFK Assassination. If even half of what was written about LBJ and his cohorts (Mac Wallace, Bobby Baker, and others) is true, then he was a real nut job and had no business ever being President or even VP. This book isn’t just about the JFK assassination, it covers LBJ’s entire political career and all the crooked crap he did. By the way, it took a while to read this one, but I enjoyed it.
LBJ was the epitome of a power hungry sociopath. The box 13 scandal, the murder of his sister, the murder of the federal judge by Mac Wallace; who was convicted of 1st degree murder but only received a 5 year suspended sentence.
I've researched the LBJ as the mastermind angle and I don't think that's the case. I think LBJ was "read in" on the plot (he was at the big dinner party at Clint Murchinson's house on 11/21/63) and he was fully on board since he was desperate to become president. However, the CIA was operating outside of the established power structure for quite some time and I don't believe they would be taking orders from Johnson.