A sex tape – a sex filmstrip, really – featuring Hollywood legend Marilyn Monroe has been unearthed only to disappear again into the collection of a wealthy New York businessman who spent $1.5 million.

Memorabilia collector Keya Morgan discovered the film while researching a documentary on Monroe. His research brought him in contact with an FBI informant who first told the federal agency about the film, which depicts Monroe performing oral sex on an unidentified man.

The FBI confiscated the footage, but not before the informant made a copy of it, which is what eventually went on sale this week, according to the New York Post.

Why was the FBI involved? According to Morgan, then-FBI Director J. Edgar Hoover nabbed the 15 minutes of 16mm film in a vain effort to prove that the man was either John F. or Robert F. Kennedy. Morgan said he based his statements on declassified FBI documents and interviews.

Morgan brokered the sale of the film to an unidentified New York businessman, who bought the tape to keep it secret and safe.

"He said he's just going to lock it up," Morgan said. "He said, 'I'm not going to make a Paris Hilton out of her. I'm not going to sell it — out of respect.'"

The film was probably shot in the 50s and most likely before Monroe's ascent to stardom. In the film, Monroe performs oral sex on a man whose head remains just out of frame.

According to Morgan, baseball star Joe DiMaggio once offered the FBI informant $25,000 for the film. The informant declined.

The FBI informant who originally copied the film has since died. The informant's son kept the copy, which Morgan said he watched himself.

"You see instantly that it's Marilyn Monroe — she has the famous mole," Morgan said. "She's smiling, she's very charming, she's very radiant, but she's known for being radiant."