The film director, the ex-lovers' tiff, and a brush with the law that came straight out of Kafka

Duncan Roy has just spent three months in a tough Los Angeles jail. But the really tough thing, he tells Guy Adams, was having no idea why he was there

A British film director arrested in Los Angeles over a dispute with his ex-boyfriend has revealed how a night in the cells turned into three unpleasant months behind bars, thanks to what he called a "Kafka-esque" misunderstanding by the US authorities.

Duncan Roy was taken in for questioning by the LAPD on 17 November, after meeting his former lover, a high-profile Malibu estate agent called Chris Cortazzo, to talk through a disagreement over a property deal.

He was promptly bailed on a charge of attempted extortion, and should therefore have been immediately set free. But for reasons that remain unclear, Roy was kept under lock and key after being informed that a "hold" had been put on his release by the Immigration and Customs Enforcement authority (ICE).

It wasn't until 7 February that he eventually emerged from custody, having spent 84 days at the Los Angeles Men's County Jail. Despite suffering from cancer, Roy was denied access to a doctor for scheduled screenings throughout his incarceration.

"It was barbaric and Kafka-esque, and it could happen to any foreigner unfortunate enough to be arrested in the US, even for something as minor as jaywalking," Mr Roy told The Independent. "We still have no clue why my release was blocked, and the agencies involved won't explain themselves."

Mr Roy's lawyer, Alec Rose, said he was baffled that his client had been locked up for so long. "We have no idea how it came about, and it seems to have been the result of an error. Once you have this 'hold' put on you, in the US justice system, it seems you can fall into a legal back hole. You get left to languish."

A spokesman for ICE said he was unable to explain Mr Roy's incarceration. A "hold" should not normally prevent release from a County Jail, he said.

On Thursday, Mr Roy appeared in Van Nuys Superior Court, in LA's northern suburbs, where he pleaded not guilty to "sending a letter with intent to extort" to Mr Cortazzo, an estate agent famed for selling beach-front homes to Hollywood celebrities. If convicted, Mr Roy, who in 2009 appeared in the US reality series Sex Rehab with Dr Drew, faces up to three years in prison. He intends to vigorously fight the charge, and says prosecutors are now seeking a plea deal which would prevent him having to serve further time.

This week's arraignment hearing marked the latest chapter in a long-running legal saga. It began in October when Mr Roy – whose directorial credits include the award-winning indy title AKA, starring Bill Nighy, and the Liz Hurley film Method – learned of structural problems at his Malibu home.

He contacted Mr Cortazzo, who had sold him the $1.37m (£860,000) hillside property in 2007, alleging that the problems were deliberately hidden at the time of purchase. In an email, he demanded $500,000 compensation.

Mr Cortazzo, who denies wrongdoing (and did not respond to requests for comment) refused. Mr Roy then allegedly threatened to blog about their relationship, which began when they met at a sex addicts' meeting in 2004.

Police and prosecutors claim that threat amounts to extortion. Mr Roy and his lawyers argue otherwise. Either way, he was arrested by five officers from the LA Serious Crime squad.

Prison was not a salubrious experience. Like many correctional facilities in California, the LA County jail is hugely overcrowded. Sheriff's deputies who run it have in recent years been forced to make a string of multi-million dollar compensation payments to inmates they have assaulted.

It is also racially segregated. "The most important thing you can do to survive there is to say you are gay," Mr Roy said. "Once you do that, they put you in a special gay section." In the gay wing, which largely contains transvestite prostitutes arrested in Hollywood, Mr Roy said the major hazards instead involved homophobic taunts from officers.

"They are barbaric, in that you see people smacked around every day," he said. "They are also extremely homophobic; but not in a particularly inventive way. I mean, they'll call you 'faggot' all the time. I remember one guard who came right up to me and said, 'What disgusts me about you faggots is your filthy lifestyle.' But having an English sense of humour helps you cope."

Mr Roy said his boarding school education, at Shrewsbury, prepared him for many indignities. During his stay, he witnessed several "weddings" between gay inmates, and countless sexual transgressions. The food was "inedible", so he survived on the contents of vending machines that sell snacks at highly inflated prices.

The lack of healthcare was harder to put up with, though. "It came to the point when I should have been having cancer tests, since I'm in the first year after a tumour was removed," he said. "But I wasn't even looked at. Every week, I put in an official demand to see a doctor and for three months I didn't see one."

Mr Roy was eventually released after his case came to the attention of the Esperanza Project, an organisation which lobbies on behalf of immigrants to southern California. Once Esperanza contacted the authorities, he was set free within 24 hours.

If Mr Roy is eventually found not-guilty, he intends to sue for wrongful imprisonment. "My lost earnings are substantial. While I was inside, I had to cancel a planned film, with Zachary Quinto, called It Gets Better," he said. "And of course, people in Hollywood are now totally petrified of associating with me. The case affects my entire career."

He is also writing a memoir of his time inside, saying he hopes to shed light on the US justice system's "inhumane" treatment of immigrants. "It's not generally white, educated migrants like me who end up in America's prisons; it's disenfranchised ones who often can't speak English and therefore who don't have a voice. That's the saddest thing of all."