“I’m not going to promote this book,” he continues. “How dare I promote it when its credibility is down the toilet?”

The book, which will be published on July 12, was excerpted in The New Yorker magazine in April. The story attracted widespread media attention and led producer-director Steven Spielberg to buy the movie rights to the book. Spielberg has lined up Sam Mendes, who won an Academy Award for directing American Beauty, to create a film of Talese and Foos’ story.

Talese has long been hailed as a master of the New Journalism, a form that emerged in the 1960s marrying shoe-leather reporting with the techniques of fiction writing. His 14 books include Thy Neighbour’s Wife, a chronicle of the sexual revolution of the 1970s, and The Kingdom and the Power, an inside look at The New York Times. He is the author of one of the classic magazine profiles of the 20th century, “Frank Sinatra Has a Cold”.

The Voyeur’s Motel is largely based on journals kept by Foos, now 82, who built a hidden walkway above some of the rooms at his motel, the Manor House, in suburban Denver. The journals describe a variety of intimate encounters among his guests, who were unaware that Foos was watching them from above through specially fitted vents.

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While the vast majority of events described in the book occurred in the 1970s, Talese does refer to incidents that allegedly occurred in the 1980s. Talese writes, for example, that Foos’ second wife “sometimes joined him in the attic” to watch guests during the mid-1980s. But Foos didn’t own the motel then, and said he had quit his Peeping Tom ways by the time he took the motel back in 1988.

Talese does note in The Voyeur’s Motel that he found some discrepancies in Foos’ accounts. Foos’ earliest journal entries, for example, were dated 1966. But the author subsequently learned from county property records that Foos didn’t buy the Manor House Motel until 1969 – three years after he said he started watching his guests from the catwalk. “I cannot vouch for every detail that he recounts in his manuscript,” Talese writes in the book.

But property records also show a series of sales and purchases of the motel from 1980 to 1988, none of which Talese said he knew about. In a series of interviews, he expressed surprise, disappointment and anger to learn about the transactions. He said he had not been aware of them until a reporter asked him about it.

“The source of my book, Gerald Foos, is certifiably unreliable,” said Talese. “He’s a dishonourable man. I know that. I did the best I could on this book, but maybe it wasn’t good enough.”

Foos vouches for his own veracity. “I can swear to this, and I can say this unequivocally and without recourse, that I have never purposely told a lie,” he said. “Everything I said in that book is the truth.”

Some of the book’s timeline of events has already been called into question, particularly an incident that Foos said he witnessed at the motel in 1977. While secreted in the attic, he said he saw a man strangle a woman to death in the room below. He said he later reported this to police, without revealing he was an eyewitness. But Talese was unable to find any official documentation of this crime, and in the book and New Yorker excerpt, he dismisses this discrepancy as a record-keeping error by authorities.

The book makes only fleeting reference to a murder that did occur at the Manor House – the unsolved 1984 homicide of a man named James Craig Broughman, apparently by an intruder.

The various sales of the motel in the 1980s came to light in April after media organisations asked about the 1984 murder and other police records on the Manor House. An Aurora homicide detective, Stephen W. Conner, conducted the property record search and found that Foos and his wife, Donna, sold the Manor House in October 1980 to Earl and Pamela Ballard, a local couple Gerald Foos knew. The Ballards, in turn, sold it in 1983 to Kyong C. LeFebre.

Foos and his second wife reacquired it from LeFebre in July 1988. The Fooses then sold it for the last time in 1995, the records indicate. Foos confirmed the general sequence of events in an interview.

Conner, who spoke briefly with Foos in April, says Foos didn’t have access to the Manor House in 1984 because he no longer owned it. “I have no doubt that Mr Foos may have been involved in some nefarious activity while he owned the Manor House. I just do not think it arose to the magnitude described by Mr Talese,” the detective says.

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Talese said it was his understanding that Foos and his family lived in the motel even after he sold it “to a Korean family” (in fact, the initial buyer, the Ballards, are not Korean), and after it was sold a second time to LeFebre. “He lived in the goddamn place,” Talese says.

In fact, he did not, according to both Ballard and Foos. Still, Foos says he had access to the annex, which he called his “sexual researcher’s station”, during the three years the Ballards owned the place.

Ballard disputes this. After buying the motel in 1980, Ballard said he locked the annex and closed off the ceiling vents that Foos had installed to facilitate his voyeurism.

Ballard, who knew Foos for years before buying the motel, confirmed that Foos had spied on guests for many years in the 1970s. “He was pretty open about that,” Ballard said. “At least he was to me.”

During the 1970s, Ballard said, Foos sometimes invited Ballard as well as another man to join him in the annex to look in on guests. Ballard said he went multiple times, but added, “I never liked Gerald. He certainly was a pervert.”

For his part, Foos called Ballard “as big a voyeur as I was”.

Foos said he was locked out of the motel altogether when LeFebre took over ownership from Ballard in 1984. At that point, he said, “I decided to get out of the voyeurism business”.