Extradition, extradition, extradition. The attention being paid to the attempts made by the Swedish government to extradite Julian Assange and what is happening to Bradley Manning in Virginia has inevitably obscured another battle being fought out behind the scenes, that of Gary McKinnon, the hacker with Asperger's syndrome who left rude messages in the Pentagon's computer system a decade ago.

Every member of both houses of parliament should by now have received a letter containing fresh details of McKinnon's medical history and that of close members of his family. The decision to make public this intimate side of his life has been taken because McKinnon's family now feel that there is a real possibility the government may bow to repeated requests from the United States and allow the extradition.

What MPs and members of the House of Lords will learn is that McKinnon's mental problems were first noted back in 1983, when he was only 17. When he was diagnosed three years ago as suffering from Asperger's syndrome, suggestions were made in some quarters that this was a convenient way for him to avoid being extradited. This new evidence – which will form part of a debate in the Lords, initiated by Lord Maginnis, on March 23 – gives the lie to that scepticism.

In the letter McKinnon's mother, Janis Sharp, writes: "On 10 February 1983 we were compelled to take my son to see a neurologist because of our grave concerns regarding the sudden deterioration in Gary's mental health and the loss of his intellectual faculties, leading us to fear that Gary may have a brain tumour." She goes on to spell out the family's painful medical history.

She had taken the decision to go public with the family's many problems because she feels that MPs and members of the House of Lords need all the ammunition available as McKinnon runs out of legal options to fight extradition.

To her credit, Theresa May, the home secretary, stayed the extradition process once the coalition government took office. She is, according to the Home Office, "looking afresh" at the medical evidence, and is asking McKinnon to submit to a further examination – which he has agreed to, provided the examiner is an expert in Asperger's syndrome.

May then has to make what may be a speedy decision as to whether allowing extradition would be a breach of McKinnon's human rights. What politicians may want to digest is the assessment made by Professor Declan Murphy – an expert in Asperger's and autism and a psychiatrist regularly used by the Home Office – that "[Gary] now has a fixed autistic-like idea, which is currently unshakable, that his best outcome is to take his own life".

Thanks to WikiLeaks, it has emerged that Gordon Brown, when prime minister, approached the US ambassador in the UK, Louis Susman, on McKinnon's behalf. Brown's reasonable suggestion – that McKinnon would plead guilty to hacking offences but would serve any sentence in the UK – was then snubbed by a secretary of state who this week has been lecturing Middle Eastern countries on tolerance and humanity.

It is perfectly possible for the United Kingdom to refuse to grant an extradition request. Life will go on. Last July Switzerland refused an American request for the extradition of the film director Roman Polanksi, who was convicted of a far more serious crime than computer hacking, and so far Hillary Clinton has not instituted a no-fly zone over Geneva.

Coincidentally, this month the National Archives released official and previously censored documents about UFOs. It was McKinnon's belief in the existence of UFOs that sent him on his weird and wonderful hacking mission through the computer systems of Nasa and the Pentagon. The Ministry of Defence documents show this was something that even quite senior government figures around the world were concerned about, although many "flying saucer" sightings have turned out to be pranks or misunderstandings.

When confidential government documents are released in 30 years, detailing discussions about a computer hacker with Asperger's syndrome who did no harm beyond embarrassment to the American military, we must hope that future generations see that our ministers stood up for decency and common sense, and did not bow to demands for an ignoble extradition.