LONDON  - A British computer hacker accused by the United States of causing more than $700,000 damage to US military systems will not be extradited because of the high risk he could kill himself, Britain's Home Secretary Theresa May said on Tuesday. Gary McKinnon, who has been fighting extradition for seven years, faced up to 60 years in a US jail if found guilty of what one US prosecutor called the "biggest military computer hack of all time". McKinnon, 46, admits hacking into Pentagon and Nasa computers under the pseudonym "Solo" but said he was looking for evidence of UFOs.