The mother of British computer hacker Gary McKinnon has welcomed Home Secretary Theresa Mayís decision to block his extradition to the US.
Janis Sharp said she was "overwhelmed" after an "emotional rollercoaster" and she said Mrs May had been "incredibly brave" to "stand up" to the US.
Mr McKinnon, 46, admits accessing US government computers but claims he was looking for evidence of UFOs.
The home secretary told MPs McKinnon was "seriously ill".
A spokeswoman for the US State Department, Victoria Nuland, said: "The United States is disappointed by the decision to deny Gary McKinnonís extradition to face long overdue justice in the United States. We are examining the details of the decision."
Mr McKinnon, from Wood Green, north London, who has been diagnosed with Aspergerís syndrome, a form of autism, faced 60 years in jail if convicted in the US.
But Mrs May said his was a "difficult and exceptional case" and there was a real risk of him attempting suicide if he was sent to the US.
Ms Sharp said her son could not speak when he first heard of the decision but then he cried and hugged her.
She said: "He felt like he was a dead person. He had no job, he didnít go on holiday... he felt worthless."
His solicitor, Karen Todner, said it was "a great day for British justice" and his barrister, Edward Fitzgerald QC, said Mrs May had been "brave".
Mr McKinnonís bail conditions, imposed since 2005, have now been lifted, meaning he can once again use a computer and also access the internet.
BBC legal correspondent Clive Coleman said it was a dramatic decision - the first time a home secretary had stepped in to block an extradition under the current treaty with the US.
Shami Chakrabarti, director of civil rights group Liberty, congratulated Mrs May and said: "It is a great day for compassion and common sense."
Mark Lever, chief executive of the National Autistic Society, said: "Weíve started to raise the profile of the vulnerability of people with autism in the criminal justice system."
Mr McKinnonís MP, Conservative David Burrowes, said: "Itís a life thatís been given back to Gary in a long dark tunnel that is 10 years. This must never happen again."
But Labour former home secretary Alan Johnson criticised the decision and claimed Mrs May had made a decision which was "in her own partyís best interests but itís not in the best interests of this country".
He said: "Gary McKinnon is accused of very serious offences. The US was perfectly within its rights and it was extremely reasonable of them to seek his extradition."
American extradition expert Douglas McNabb said the US Attorneyís Office would be furious.
Mr McNabb said he suspected it would ask Interpol to issue a red notice - making other nations aware there was an outstanding arrest warrant for Mr McKinnon in the US - which would mean he could be arrested if he left the UK.
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