Frank Sinatra believed Marilyn Monroe was murdered, an explosive new book reveals.

Sinatra’s close friend and former manager Tony Oppedisano reveals all in his memoir Sinatra and Me: In The Wee Small Hours.

People published an excerpt from the book, which includes a bit about the singer being suspicious about what had really happened when Monroe was found dead from a suspected drug overdose on August 4, 1962.

“Frank believed she was murdered,” Oppedisano writes, “and he never got over it.”

Oppedisano claims Sinatra and Monroe were close friends but not lovers, despite rumours to the contrary.

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Although Sinatra thought the star was beautiful and funny, Oppedisano writes, “Frank felt she was too troubled, too fragile, for him to sleep with and then walk away.”

Monroe did trust Sinatra with secrets regarding her affairs with John F. Kennedy and Robert F. Kennedy, though.

Oppedisano says of the affairs’ abrupt ends, “Marilyn told Frank she didn’t understand why they’d shut her out completely once she stopped having sex with them.”

The weekend before her death, Monroe spent time at the famous Cal Neva Lodge, outside of Lake Tahoe, which was partially owned by Sinatra. She was reportedly there to spend time with her ex-husband Joe DiMaggio.

Monroe had allegedly decided to make a press announcement the following week to confirm the pair were getting back together.

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The press conference then fuelled rumours Monroe was going to share details of her relationships with JFK and RFK, which Sinatra thinks contributed to her untimely death.

Oppedisano writes, “Frank said she’d never have spilled about the Kennedys because she still had feelings for [Jack.]”

“Frank believed if the press conference hadn’t been announced, she would have lived a lot longer.”

Sinatra’s attorney Milton “Mickey” Rudin, who also worked with Monroe, also thought the actress had been killed. Plus, rumours circulated among mob boss Sam Giancana’s men, some of whom claimed involvement.

Oppedisano claims in the tell-all book that Sinatra had several sources who told him the same story regarding Monroe’s death: “She’d been murdered with a Nembutal suppository and Robert Kennedy or the Mob was involved.”

“Conspiracy theories abound and I can’t lay them to rest,” Oppedisano writes of Monroe, adding that Sinatra remained haunted by her death until he passed away on May 14, 1998.

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