These highly unusual measures were just some of those employed to ensure the identity of the whistleblower and former spy known as Witness K forever remains a closely guarded secret.

While his name will never be made public, the Sunday Canberra Times can now reveal rare insights into the character and past of the former Australian Secret Intelligence Service officer, who was recently handed a suspended jail sentence for helping expose this country's 2004 bugging of impoverished ally East Timor.

Partially redacted court documents tell the story of a man with "a long-standing commitment and sense of duty to the well-being of his country".

But Witness K endured no shortage of personal turmoil during a life of service.

Doctors' reports tendered to the ACT Magistrates Court show he joined the Royal Australian Navy as a teenager and was sent to sea at just 18, serving in the Vietnam War.

He feared he was going to die during an incident where he was shot at, leading to post-traumatic stress disorder with associated anxiety and depression.

Witness K has had trouble sleeping ever since, experiencing nightmares and flashbacks.

"When he returned from the first overseas deployment he apparently was edgy, irritable and [a] changed person," a psychiatrist wrote in one report.

"This apparently was picked up by his mother who said that he had gone 'crazy' observing his behaviours."

Another psychiatrist opined that Witness K was "startled easily by any unexpected noises or people approaching from behind him".

"He was excessively on guard and on edge," they wrote.

Now an elderly grandfather, Witness K has had issues with binge-drinking since his time in the Navy.

But the man has also used some positive coping strategies, reporting a love of music, fixing guitars, physical fitness and endurance exercises.

"He is reliant on his dear wife to support and prompt him for most activities of daily living," a psychiatrist's report reads.

Witness K did not seek help with his mental health demons for many years, but "significant psychological" problems together with insomnia and mood disturbances led to him taking stress leave during his time working in the federal public service.

He broke down in tears while in the office in 2005, the year after Australian spies bugged a government building in East Timor during sensitive negotiations over lucrative oil and gas reserves.

It was this controversial episode of espionage over which Witness K was last month convicted of conspiring with his former lawyer, ex-ACT attorney-general Bernard Collaery, to illegally reveal classified information.

Witness K ultimately left ASIS after being overlooked for a promotion, believing he had been "set up for humiliation" and discriminated against because of his age.

Now retired for more than a decade, Witness K is these days reportedly "much more settled after being removed from the ... stresses from work".

He is said to lead "a quiet but active life", which includes playing the guitar and spending time with his grandchildren.

"At his appointments he was always polite, well-mannered and cooperative," a psychiatrist wrote of the man.

"He was careful not to talk about the details of his classified employment.

"I considered he had a long-standing commitment and sense of duty to the well-being of his country."

The lengthy of list of awards bestowed upon Witness K would seem to support this opinion.

A list of "at least some of them" takes up a full A4 page, with a note pointing out there may be more that remain classified.

The awards, issued for Witness K's work in both the Navy and intelligence services, speak of "a job well done" through "loyal" and "meritorious" service.

One makes mention of "a grateful nation" expressing its thanks.

This is something whistleblower advocates will surely note following Witness K's conviction and sentencing, with that same "grateful nation" now considering a once-celebrated servant a criminal.

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: