Now his lustre has been burnished all the brighter by his refusal to kow-tow to the might of the American TV network ABC. Furthermore he has become the first person in 57 years to turn down a prestigious Peabody award because it would have been shared with what he believes is a duplicitous media monster.
When he found the hidden Khmer leader last July, Thayer was described as having spent 10 years on the trail of Pol Pot.
"In fact that is rather a lot of hype," he says. "It's not like I had an obsession with Pol Pot. I was a Cambodian correspondent and lived there for six years. I also lived in Thailand for another five years so obviously there were plenty of other Cambodian and Asian stories that I covered.
"But I had always thought that Pol Pot was one of the last great interviews in the world. Here was a household name the world over who had never explained himself. He was perhaps the most effective 'secret leader' of the twentieth century.
"So all the time I lived in Cambodia and Thailand I kept one eye on Pol Pot. I made numerous trips into the jungle and built up contacts with Khmer Rouge leaders. And I made constant requests for access or an interview with Pol Pot.
"The break came in June 1997 when I was expelled from Cambodia for exposing connections between the Prime Minister and heroin traffickers. I decided to write a book so I spent a lot of time just sitting in a room with the Khmer Rouge's clandestine radio station on in the background. I heard then that the defence minister had been deemed a traitor and executed so I immediately went to my Khmer Rouge contacts who told me about serious infighting within the leadership and that Pol Pot had been overthrown.
"They even announced Pot's overthrow on the radio but no one believed them and that became the basis for my argument for getting access. No one would believe he had been overthrown unless a western journalist got in to prove it.
"From there I began the process of getting into one of the most impenetrable places in the world. The only foreigners to have been there before were the three guys who were kidnapped and executed. It was made all the harder because last July a civil war broke out in Phnom Penh and I had to fly to Bangkok and try from there by illegally crossing the border, not to mention the front lines of the Phnom Penh civil war and the front lines of the Khmer Rouge civil war.
"Once me and my cameraman were in a hotel over the border I had to phone a number in Europe to tell them my room number before being infiltrated into the jungle.
Thayer never did actually interview the leader responsible for the deaths of an estimated one million Cambodians. Instead, he filmed two hours of Pol Pot being denounced at a classic Maoist show trial.
Nevertheless, his story was dynamite, and as soon as it became known that he had footage, pictures and a story he was bombarded with hundreds of calls from news organisations. His main priority was to have the print story go in the Far Eastern Economic Review, which he had worked for as a freelancer for years and which had supported him for six months while he tried to get to Pol Pot in the jungle.
But he sold the North American television rights to his footage to ABC for $350,000 - "Mainly because ABC's Ted Koppel is as good as it gets on American TV. He seemed like the last honourable guy."
But now Thayer is seriously pissed off at ABC. The network's PR department got hold of the footage and did a major number on it. They made enhanced video-grabs which they gave to newspapers under an "ABC Exclusive" tag. This meant that, using ABC's released material, the New York Times was able to run Thayer's story before he had even started writing for the Economic Review. And by putting out the video grabs and downloading images onto its Web site, ABC ruined Thayer's chances of selling the stills from his trip into the jungle.
"Basically they said 'f*** you' to my lawyers because they knew their lawyers could eat a freelancer alive," says Thayer. "It was an outrageous ethical violation. They then refused to pay me my agreed fee until I signed something saying that they had done nothing wrong. It took 10 months to get my money and they only paid up because they knew when I had won the Peabody that it would turn into a PR nightmare."
ABC claims that its pre-broadcast publicity was perfectly normal behaviour and Thayer was naive for not understanding this.
Thayer believes the network's behaviour speaks volumes about the state of US television news. "ABC have one correspondent for the whole of Asia so they take freelancers' work and try to take credit for it. The function of people like Koppel is to prove that there is a serious side.
"But in reality to them the function of journalism in a free society is no more than delivering audiences to advertisers."