The FBI is rotting from the top, turning the federal agency into a criminal organization that routinely violates Americans’ constitutional rights and commits felonies all the way up to murder and perhaps political assassination.

That’s not some politically fueled conspiracy theory meant to undermine investigations related to the current president, his advisers and Russia. Instead, it’s the acknowledged, documented history of the bureau and its Counter-Intelligence Program under Director J. Edgar Hoover during the 1960s.

The question at the heart of best-selling novelist Steve Berry’s latest thriller, “The Bishop’s Pawn,” is whether COINTELPRO played a part in the assassination of Martin Luther King Jr. on a hotel balcony in Memphis on April 4, 1968.

“It’s one of the great mysteries of the 20th century,” Marietta native Berry said in a phone interview in advance of an appearance at the Marcus JCC on Sunday, March 25. Despite hundreds of speculative books and because of the lack of an apolitical investigation, “we have no idea what happened in Memphis.”

The Bishop’s Pawn
By Steve Berry
Minotaur Books, 352 pages, $28.99

He said he was inspired to tackle that mystery in part by listening to King’s full “I’ve Been to the Mountain” speech, delivered the night before his death. Berry said it sounds like a man who knew he was about to die, and the author emphasizes the point by reprinting much of the speech near the novel’s climax.

Berry brings Navy veteran and bookstore owner Cotton Malone back for the 13th time. This adventure, told entirely from Cotton’s perspective for the first time, begins on the upcoming 50th anniversary of the King assassination, jumps back nearly two decades to serve as an origin story for Cotton’s involvement as an investigator for a secret Justice Department unit, and fills in the blanks with documents, illegal wiretap recordings and eyewitness memories from the 1960s.

Just to spice things up, Berry incorporates a Cuban killer linked to Fidel Castro, the geography and history of Florida’s Dry Tortugas, and a legendary 1933 Double Eagle gold coin.

Devoted to weaving history through his fiction, Berry depicts King as a human, not a saint. He cheats on his wife, smokes too much, has a bad diet and struggles with self-doubt and depression as he sees his movement slipping off his path.

“I think King himself would be a little bit appalled at his saint status,” Berry said. “He always considered himself a humble human being.”

But Berry said he was respectful of King’s message, and he creates a man even more worthy of admiration for overcoming his human faults and frailties.

Meanwhile, Hoover and COINTELPRO, which Berry said was probably the most corrupt government-created organization in American history, seem so much worse for working so hard to destroy the lives of King and others and to stop the civil rights movement in its tracks.

Berry acknowledged interesting parallels to what the FBI did at Hoover’s whim half a century ago and what federal authorities could do with electronic surveillance and other techniques today. But there’s a key difference between government corruption then and now, he said. “Today, all those people go to prison. In those days, they got away with it.”

Berry doesn’t solve the Memphis mystery. But he provides a possible explanation that’s shocking and plausible, and he entertains the reader with a thriller that pushes just beyond the limits of the forgotten history he weaves together.

Who: Steve Berry
What: Page From the Book Festival conversation with CNN’s Nadia Bilchik
Where: Marcus JCC, 5342 Tilly Mill Road, Dunwoody
When: 7 p.m. Sunday, March 25
Tickets: $10 for JCC members, $16 for others; atlantajcc.org/bookfestival or 678-812-4005