In the 1980s and early 1990s, the few computers that did have the ability to communicate with each other were owned by either US government agencies or computer companies based in Silicon Valley, California.

During this time, exciting new software programmes were freely available online, as computer geeks devised and generously shared them with other users.

Kremen, still in his 30s, hit upon the idea of packaging and selling those software programmes for $99 a pop. Soon, he was one of the first sellers of lucrative anti-virus software, a smart decision after the first computer virus hit 10% of the world's computers in November 1998, and he was quickly well on his way to becoming a dotcom high flyer.

Kremen formed a company called Electric Classifieds Inc.

This is when he did something that potentially altered the course of his life: he acquired two domain names: the first was match. com . . .

now one of the world's biggest dating sites, which the board of Kremen's company later insisted on selling against his better judgement. The second was sex. com which Kremen wisely decided to keep for himself.

At its peak, sex. com would earn $100m a year with five million page views per day and become the most valuable real estate on the Internet. It would soon earn a sizeable fortune, not for Kremen, but for Cohen, the daring conman who would plot to steal it.

As journalist Kieren McCarthy writes in his book, Sex. com: One Domain, Two Men, 12 Years & the Brutal Battle for the Jewel in the Internet's Crown, just because the site didn't physically exist, didn't mean that it couldn't be stolen.

"Stephen Cohen was able to snatch sex. com and walk into a life of untold weath and luxury, " McCarthy says. "But Cohen had underestimated the determination of Gary Kremen to get his property back."

McCarthy, a noted blogger and journalist who writes for The Guardian, The Times and The Independent in London, has written about the saga for over five years, gaining access to both Kremen and Cohen.

His story shows how, as Cohen proceeded to make millions of dollars from the site, Kremen fought tooth-and-nail to win it back for over a decade. It was a struggle that would put Cohen in prison, lead an embattled Kremen into drug addiction, re-write the law and shape Internet history.

The battle over the domain and, ultimately, the website it would create, began in 1995 when the name "Gary Kremen" on sex. com's electronic ownership records mysteriously changed to "Stephen Cohen". It was an innocuous start to an epic battle. For such a valuable commodity, it only took a simple case of forgery by a convicted conman. Cohen sent a phony . . . but successful . . . fax, littered with bad spellings and grammar to Network Solutions, the company that leased domain names for $50 each, instructing it to change the ownership details.

Unbelievably, considering what was at stake, that fax . . . plus a persuasive phone call to a Network Solutions employee . . .

worked.

The email address on the electronic ownership of sex. com also changed to steve@liberty . com from gkremen@netcom . com. Kremen noticed this too, but thought it was a temporary glitch.

It was a costly mistake. Soon, all the contact details changed too.

When Kremen finally called Network Solutions to ask what the hell was going on the company said it would investigate the matter. Kremen then received a call from a "Bob Johnson" from Network Solutions, who told him that Cohen owned the sex. com trademark.

"It was a believable story, " Kremen said later. He didn't know then that Bob Johnson didn't exist.

He had actually been speaking to Cohen, who was pretending to be a Network Solutions employee. And that was all it took for the theft of the century.

Having lost the domain name under such murky circumstances, Kremen next called the number listed on the new electronic ownership database. He called the man who would be his adversary for the next decade.

Characteristically belligerent and brazen, Cohen recalled, "He made some off-the-wall comment: I'm sex. com, you're not sex. com'. I told him to go f*** himself and hung up." A 10-year game of cat-andmouse would follow, as Cohen's arrogance was only matched by Kremen's frustration and escalating addiction to cocaine and crystal meth.

Through the 1990s, Cohen used sex. com as an advertising springboard for other pornography sites, pulling in $500,000 a day at its peak. With that kind of money, and his own lawyers, he could blindside Kremen all the way.

In July 1998, Kremen sued Cohen with the financial help of two other Internet entrepreneurs who had their own reasons for taking Cohen down. At long last, Kremen finally won his case and, in November 2000, he was finally given back sex. com, five years, one month and nine days after it was stolen. In March 2001, Kremen was further awarded $40m in lost earnings and another $25m in punitive damages. It was a landmark case. Before the judgment, domain names were regarded as being leased for an annual fee, unbelievable when you take into account their value to companies like Amazon and eBay.

But the judge in the case ruled that registering domain names was no different than . . . as he said . . .

"staking a claim to a plot of land at the title office".

But that was merely the end of the beginning. Kremen's legal team was too busy enjoying their victory celebrations to freeze Cohen's bank accounts. Two hours after the $65m award was announced, Cohen began transferring the funds to his offshore accounts. The judge issued a warrant for his arrest, ordering him to remain in prison until he returned millions he had transferred out of the country. But Cohen fled to Tijuana, Mexico, where he went on the run for four years. In a last-ditch attempt to get him back, Kremen posted a notice offering a $50,000 reward for Cohen's return to the US (he posted it on sex. com, appropriately enough). Cohen was eventually brought back to the US after a shoot-out involving Mexican police and US bounty hunters to face justice, and jailed for 14 months for contempt of court.

Over the years, Kremen burnt through a reported $5m in legal fees and sex. com was not earning anything near what it had during its peak. Last December, Cohen was released from prison and ordered to surrender assets to Kremen. But, on 26 February, Cohen pleaded poverty and asked the judge to erase his $65m debt.

"I own no stocks, bonds, securities, jewellery and I have no trusts, " Cohen told the California judge. And Kremen? Even after he was declared victorious, the paper chase for Cohen's missing millions from sex. com is still costing him $25,000 a month.

According to Kieren McCarthy, who has followed the case for the last 12 years, Cohen repeatedly taunted Kremen, telling him he'd never see the $65m.

"In all the years you've been chasing me, " Cohen reportedly told Kremen, "you have never got a single asset in my name. And you never will."

Sex. com: One Domain, Two Men, 12 Years & the Brutal Battle for the Jewel in the Internet's Crown, by Kieren McCarthy is published by Quercus Books