Clearly, my title explains the truth about Jim Garrison - that he was chasing a delusion. A mythical belief in a JFK conspiracy....and since he could never actually find it, he had to make one up. And, in the process, he ruined lives.
The subtitle, The Great Accuser, comes from Harry Connick, Garrison's successor as District Attorney of New Orleans. He came up with it - here's an article from the Times-Picayune.
And, where did Harry Connick get it from. Well from the New Testament.
From 1 Peter 5:8
Curb every passion, and be on the alert. Your great accuser, the Devil, is going about like a roaring lion to see whom he can devour.