Gary McKinnon Research Continued

Gary McKinnon, who was diagnosed last August as having Asperger's syndrome, readily admits to hacking into US military computers.

But the 43-year-old from Wood Green, north London, denies malicious intent or causing hundreds of thousands of dollars of damage as alleged by the US government, which accuses McKinnon of "the biggest military computer hack of all time".

McKinnon, or Solo as he was known online, got his first computer when he was 14 and has been a computer whiz ever since. He left school at 17, and became a hairdresser. In the early 1990s, some friends convinced him to get a qualification in computers. After a course, he started doing contract work in computing.

In the late 1990s, McKinnon developed an interest in aliens through an internet-based group of UFO enthusiasts called the Disclosure Project in the late 1990s. The group had collected more than 200 testimonies – some from people who have served in the US military – that "confirm" that extraterrestrials exist.

McKinnon, who describes himself as a "bumbling computer nerd", decided to use his computer expertise to hack into US government computers because he believed the US was withholding critical information about aliens.

"It wasn't just an interest in little green men and flying saucers," McKinnon said. "I believe that there are spacecraft, or there have been craft, flying around that the public doesn't know about."

McKinnon's computer expertise allowed him to run rings round American government security experts and there is more than a whiff of revenge in the determination to extradite him. But the harder the US tries, the more it turns McKinnon into a cause celebre for civil rights groups,Conservative MPs and the Daily Mail.

Between 1999 and 2002 McKinnon broke into the most secure computer systems in the world from his north London flat. Using a computer language called Perl and a cheap PC, McKinnon linked a number of computer systems to search for US databases that were not protected by a password. "I could scan 65,000 machines in less than nine minutes," McKinnon said.

McKinnon unearthed unprotected computer systems operated by the US army, the navy, the Pentagon and Nasa. On every system he hacked, he left messages.

"It was frightening because they had little or no security," he said. "I was always leaving messages on the desktop saying, 'Your security is really crap'."

But one message has come back to haunt him. "I said US foreign policy was akin to government-sponsored terrorism and I believed 9/11 was an inside job. It was a political diatribe," he admitted.

McKinnon's search for UFO material on US computers turned into an obsession. As he investigated high-level computer systems in the US, his life in Britain fell apart. He lost his job and his girlfriend left him. Friends told him to stop hacking, but to no avail.

"I'd stopped washing at one point. I wasn't looking after myself. I wasn't eating properly. I was sitting around the house in my dressing gown, doing this all night," he said.

His behaviour showed all the characteristics associated with Asperger's syndrome – an obsession with certain activities and interests and a level of "social naivety" in evaluating the consequences of one's actions.

Prof Simon Baron-Cohen, who diagnosed McKinnon with the condition, has said: "We should be thinking about this as the activity of somebody with a disability rather than a criminal activity."

Because he could penetrate US computers so easily, McKinnon got careless and started leaving behind clues. At one point, McKinnon began posting anti-war diatribes on the screens of the US government computers that were his targets.

He was caught as he tried to download a grainy black-and-white photograph which he believed was an alien spacecraft from a Nasa computer at the Johnson space centre in Houston, Texas. McKinnon was easily traced because he used his own email address.

"I think I almost wanted to be caught, because it was ruining me. I had this classic thing of wanting to be caught so there would be an end to it," he said after his arrest.

Gary McKinnon