Marilyn Monroe, the curvy actress who became a household name in the 1950s, has fascinated the world even decades after her death. Southern California cosmetic surgeon, Norman Leaf, says that he may hold the answer to at least one of her beauty secrets: a set of X-rays and doctor’s notes that prove Monroe had plastic surgery.

"I've been looking at it and treasuring it and keeping it under lock and key and hidden away in my safe," Leaf said of Monroe's files and X-rays.

According to ABC News, the X-rays are of Monroe’s face, nose, and the roof of her mouth. The notes were written by surgeon Michael Gurdin and date back to 1958 when Monroe came to the doctor under the alias “Joan Newman” complaining of an issue with her chin.

“They had put a chin implant in [in the early 1950s] and it was made of carved bovine cartilage," Leaf said. "They didn't have silicone chin implants in those days... As what typically happens with that, it absorbed over the years."

Martin Nolan, executive director of Julien’s Auction House in Beverly Hills, Calif., says that the records are authentic celebrity memorabilia that people will be chomping at the bit to buy. He predicts the files will sell for anywhere between $15,000 and $30,000 at auction.

"Keep in mind, this is pop-culture history," Nolan said. "[Marilyn's records] date back to the 1950s. Today there are laws preventing the release of such information, but this is prior to that law."

"Even though X-rays are not tangible like a musical instrument or clothing," he continued. "It's part of the story of Marilyn that people are buying. There is such a demand for her worldwide even though it is 50 years since she passed away. Honestly, I could have an auction every day for Marilyn Monroe and the items would be sought after."

The auction is set to take place on Nov. 9 and 10.