Robert Slatzer met Marilyn once in 1952 whilst she was filming Niagara. They had a couple of photos together and since her death, he made many false accusations and claims.
The first claim is that he married Marilyn on 4th October 1952 in Mexico. He stated they had the wedding certificate burnt as the studio didn’t want them to get married. However, on the date that he states they travelled (3rd), Marilyn is photographed at the Photoplay Awards in Los Angeles. There is also a cheque made out to Jax in Beverly Hills on the 4th of October 1952. Marilyn was also already dating Joe DiMaggio at the time.
He additionally states they were very close until she died and he had seen a red diary containing government secrets. However, there are no photos other than those in 1952 or letters or in fact any correspondence or record of him being in Marilyn’s life. Biographies such as the one by Anthony Summers are based largely on the testimony of Slatzer (and Jeanne Carmen who never met Marilyn) which is why many Marilyn fans don’t use the book (or Summers) as a reliable source of information.
While filming scenes at Niagara Falls, [Monroe] was asked by a twenty-five-year-old visitor from Ohio named Robert Slatzer to pose with him for snapshots. For such impromptu photos and importuned autographs, no public figure was ever more generous and cooperative with admirers and strangers than Marilyn, nor was any more exploited before or since her death…In 1972, with Marilyn conveniently unable to contradict him, Slatzer approached journalist Will Fowler with a short, incomplete article in which Slatzer speculated that Marilyn Monroe’s death was part of a political conspiracy… “Too bad you weren’t married to Monroe,” Fowler said, unimpressed with Slatzer’s proposal. “That would really make a great book.” Soon after, Slatzer contacted Fowler again, saying he had forgot to mention that he had indeed been married to Marilyn. “Slatzer made a career of being a pretender,” according to Fowler, “selling gullible talk show producers who don’t do their research very well with the deception that he was married to Marilyn. He was never married to her. He met the star only once, in Niagara Falls… He never met Marilyn before or since.”… Among the most persistent but injudicious of his assertions is his absurd claim that he spent the weekend of October 3 to 6, 1952, with Marilyn Monroe in Tijuana, Mexico, where they were married on October 4… Quite apart from the fact that Marilyn was in Los Angeles that entire weekend, Slatzer could never produce a written record of the union or its dissolution.Donald Spoto, The Biography