This article is based on information from the book "The Greatest Hoax on Earth: Catching Truth, While We Can" by Alan C. Logan, which provides a comprehensive look at Frank W. Abagnale's claims throughout his career. The book is very well researched and provides extensive citations to demonstrate that Abagnale's claims are mostly false or in a few cases, greatly embellished.
In addition to Abagnale being debunked before, others expressed doubts about him along the way. One of the first to show doubt was the Galveston Daily News in an article published on January 27, 1977. As explained by Logan:
Page 31: ".. the Galveston Daily News was more cautious than most major media outlets would be in the future, noting that Abagnale had self-styled himself as "the most preposterous hoaxer who ever hoodwinked the world" with his claims that he "has assumed five different personalities and professions."
Journalist Soll Sussman, who wrote the article, did cast doubt but note how relatively mild it was, and that it did not directly challenge Abagnale and his claims. From a talk Sussman gave:
Page P35: "I'm just waiting for someone to call me with the news that Abagnale is really just a little old pizza twirler, and this is all a con," said Sussman in his closing. (1977)
After Abagnale's book was published, a vast majority of journalists gave it praise without questioning the content of it in any way. Two notable exceptions:
Page 108: Elizabeth Wheeler of the Los Angeles Times was one of the few exceptions. "According to his breezy and self-serving book, Abagnale impersonated an airline pilot, a doctor, a lawyer, and a professor, picking up oodles of money and enough women to qualify for a Guinness Record. He presents himself as a thief so charming that even the bilked love him, "wrote Wheeler. "Sounds like another con to me," she concluded.
Page 109: After Abagnale's book was released, Linda Stowell of the Arizona Republic appeared to be among the skeptics. When Abagnale passed through Phoenix in 1981, telling his tales to the Institute of Internal Auditor, she raised questions about his content, but also his 'big sell" approach. She noted he was peddling audio-visual training programs for $175, and charging bankers $1,000 per lecture for information law enforcement experts offered for free. [..] Stowell was not buying the flim-flam and wondering why the bankers were.
In a 2014 interview, Abagnale was given a simple but effective question, asking how we knew that his story was true. Abagnale's answer was not polished like most of his talks:
Page 192: Swedish TV host, Fredrik Skavlan, did ask a question that appeared to make Abagnale flinch. "How do I know that everything you tell me now is true?" asked Skavlan in 2014. The grifter seemed really taken aback by the question. "Oh, it's been documented for so many years and written, and, ah, as you know it's been a book, a movie, a Broadway musical and now a very popular television show in America," replied the con man, "Ah, so, it's been researched and documented so many times."
One of the most effective and damning cases of Abagnale being called out came from a college. Before speaking to their students, they asked Abagnale to affirm that his story was true. A smiple request:
Page 315 - 316: The University of South Carolina had a novel idea - a truth affidavit. They asked Abagnale to sign an official document attesting to the truth of the content of his lecture - a simple request for a now reformed con man. [..] Abagnale refused to sign it. Insulted, he canceled the event. [..] Not long afterwards Abagnale announced he was canceling all university talks indefinitely. [..]
In 1978, the best summary of Abagnale's claims only took three words:
Page 78: Ron Ziskin, the producer of KGO-TV's "A.M. San Francisco" put it in plain language when he just said, "We were had."