An autistic man accused of hacking into US government computers would be at "high risk" of killing himself if he is extradited to America, a court heard.
Lauri Love, who has Asperger's Syndrome, is accused of stealing huge amounts of data from US agencies including the Federal Reserve, the Department of Defence, Nasa and the FBI.
American authorities want the 31-year-old, who lives with his parents in Suffolk, to stand trial there over charges of cyber-hacking, which his lawyers say could mean a sentence of up to 99 years in prison if found guilty.
But extradition to the US for legal proceedings and a possible long jail term could cause his health to deteriorate and lead to a mental breakdown or suicide, Westminster Magistrates' Court was told.
His family and lawyers want him to face legal proceedings in the UK, where he can be close to his parents - described in the hearing as his "life support".
And medical experts warned that he could be a suicide risk if transferred to America for trial
Autism expert Professor Simon Baron-Cohen, from Cambridge University, said: "He doesn't want to die, but his mental health is so dependent upon being at home with his parents that being detained for an indefinite period in an American prison system he would experience a deterioration in his mental health so much that he would no longer be able to impose any restraint on his behaviour to stop him committing suicide."
Mr Love's father, a prison chaplain, said: "In regard to my son ... Lauri is somebody who strikes me as somebody who will do this. The probability is quite high."
The court heard that Mr Love, an electrical engineering student at the University Campus Suffolk, is accused of working with others to carry out a series of sophisticated cyber attacks on computer networks in the US from the UK in 2012 and 2013, breaking in via the "back door" to access personal information of thousands of government staff, as well as credit card details.
Peter Caldwell, prosecuting for the Crown Prosecution Service on behalf of the US authorities, said the hacks had "caused harm" by misusing people's personal data, and that Mr Love had bragged about it in online hackers' chat rooms under aliases such as "Peace" and "Root".
But his lawyer Ben Cooper said Mr Love's case was a "paradigm" to that of Gary McKinnon, another alleged cyber-hacker with Asperger's who was eventually spared extradition after a decade-long battle when the Home Secretary intervened.
Theresa May introduced a "forum bar", which allows courts to block extradition if it is in the interests of justice to have the person tried in Britain instead.
Mr Cooper, who said the US justice system pressured people into pleading guilty, added that Mr Love's case was "almost identical" to Mr McKinnon's, telling the court: "If ever there was a case for the forum bar to succeed, this would be it."
During the hearing Mr Love, who is wanted in three US jurisdictions - New York, New Jersey and Virginia - sat in the dock making origami models of roses and an intricate geometric star.
Rev Alexander Love told the court his son was "exceptionally gifted", but developed mental health problems while still at school, crippling him socially.
The court heard that as well as Asperger's, which was diagnosed quite late in his life, Mr Love has suffered from depression, anxiety, psychosis and suicidal thoughts - including voices telling him to kill himself - as well as asthma and extremely bad and painful eczema.
Mr Love now puts his hacking skills to good use, running a business with a friend advising companies how to beef up their cyber security.
His father said: "He seems to be gainfully using his knowledge for the betterment of others, and I find that to be quite gratifying."
But, telling the court that "it is breaking my soul to be saying things like this", he added that his son says that if it wasn't for his parents he would have killed himself, saying: "We are keeping him going and we are becoming, in a sense, his carers."
He added: "We come home and on certain occasions we just don't know if Lauri is going to be alive ... the possibility that he will take his own life is inordinately high."
Prof Baron-Cohen warned that Mr Love had already discussed taking his own life, and had even thought-up ways to prevent his methods being detected by authorities.
Dr Thomas Kucharski, an American forensic psychologist and expert on mental health in the US prison system, warned of the impact of being kept in isolation - a likely result of Mr Love being extradited.
He said: "It is widely recognised that isolation is a very detrimental process for people without any psychiatric condition, it is only magnified in someone with a psychiatric disorder."
He added that Mr Love would likely become "highly victimised", and it was "not likely" he would get the care he needs in the American correctional system.
And Professor Michael Kopelman, a psychiatrist who has assessed Mr Love, added that there was a great risk that he would become unfit to plead.
He said: "If his depression gets worse, if he becomes psychotic, if his eczema and asthma get worse, it may well affect his mood state to think rationally and instruct lawyers and be fit to plead.
"There is a real risk, I cannot say that it will definitely happen. He will need to be continually monitored."
He added that he thought he would be fit to stand trial in his current state.
The hearing continues on Wednesday, when Mr Love will give evidence.