That is the picture that emerges from Federal Bureau of Investigation documents now published on the Internet.

Timothy Leary advocated drugs all his life

When Timothy Leary died from prostate cancer in 1996 at the age of 76, obituary writers focused on his experimentation with drugs, his counter-culture history, and how Mr Leary chronicled his slow death via the Internet.

The former Harvard professor of psychology had preached anti-establishment slogans all his adult life.

But after he was jailed on narcotics charges in 1974, Mr Leary began cooperating with FBI agents investigating his 1971 escape from a California prison.

He had been helped by members of the radical Weather Underground group to escape from the jail and, after hiding in a series of safe houses, he was smuggled out of the country with the help of a false passport and other fake documents provided by the Weathermen.

Change of heart

After being extradited from Switzerland and returned to a US jail, Mr Leary decided to cooperate. He told FBI agents this was not only because he wanted to be released, but also because he had developed a desire for a collaborative and honourable relationship with law enforcement officers.

"I want get out of prison as quickly as I can," he told the investigators. "And I believe that telling the total truth is the best way to get out of prison."

"I prefer to work, I'm never going at it illegally ever again," Mr Leary continued in his statement, " but I would prefer to work constructively and collaboratively with intelligence and law enforcement people who are willing to forget the past."

Mr Leary justified his decision by saying he wanted to continue contributing to public debates.

"I still have a lot to say ... it's part of a longer range plan of mine," he said according to the documents.

Government support for a reduction of the jail term

His evidence does not appear to have led to any arrests or convictions, although at the time the investigators were convinced it would contribute to the US government's fight against the so-called New Left.

"All parties are agreed that the interview provides the basis for some federal action against culpable principals and conspirators in this and other matters," concludes the FBI report.

Much of it involved naming members of the Weathermen and detailing their role in his escape.