James Patterson has a theory about Marilyn Monroe‘s death.

The prolific author, whose upcoming autofiction The Last Days of Marilyn Monroe: A True Crime Thriller touches on the life and death of the Hollywood icon, believes Monroe was likely murdered due to her connections to powerful figures such as President John F. Kennedy, U.S. senator Robert F. Kennedy, and Frank Sinatra.

“I think that she was treading in very dangerous waters,” Patterson told The Hollywood Reporter in an interview published Nov. 21. “They told her stuff, and she kept track of it. She had information that was kind of dangerous.”

And having researched Monroe’s career with co-author Imogen Edwards-Jones for the book, which includes a disclaimer in the fine print describing itself as “a work of fiction,” the 78-year-old said, “A lot of people don’t know the story.”

“There’s a lot of stuff I didn’t know,” he continued. “I didn’t know much about the death scene.”

Patterson added, “The key is, a lot of people know about her a bit, but not that much. You’d be surprised.”