The former public servant told penfriend Irene Finke she was “right” and that he would never return to the treasury department.

Mr Eastman said he was "emotionally exhausted by this 10 year battle with the public service, which I have lost".

Prosecutors in the murder trial of Mr Eastman, accused of the 1989 assassination of police chief Colin Winchester, read to the jury a number of letters sent by Mr Eastman to friends and officials.

Mr Winchester, an Australian Federal Police assistant commissioner and Canberra's most senior police officer, was shot twice in the head after he had pulled into the driveway of his neighbour’s home in Deakin.

The neighbour, the trial has heard, was an elderly woman who felt safer with a car in her driveway.

Prosecutors have pointed to Mr Eastman’s desperation to return to the public service as one path of his motive towards killing Mr Winchester.

The second path was a charge of assault against Mr Eastman following an altercation with a neighbour.

The Crown says the two paths converged. Mr Winchester met with Mr Eastman and said the charges would not be dropped - and, the Crown says, effectively sealed Mr Eastman’s fate on the return to work.

Mr Eastman, 72, has pleaded not guilty to murder.

He has denied too the Crown's theory of his motive to murder Mr Winchester.

Many of the letters read to court on Wednesday were to and from Mr Eastman’s German penfriend Irene Finke.

In a letter from January 1987, Mr Eastman said he wanted to go back to work because it was boring without a job.

He was on a pension of 12,000 pounds per year, a figure he called very low and that he had to watch every cent.

It’s “terrible to be a physically healthy man, highly intelligent, only 41 and to feel society has put you on the scrap heap already,” he wrote to Ms Finke.

His job in insurance was "cup of tea".

He said he would have preferred, in order of preference, to return to the public service, become a political journalist, study German or teach in a high school.

Mr Eastman, an economics graduate from Melbourne, said he was "emotionally exhausted by this 10 year battle with the public service, which I have lost".

In other correspondence with the public service, Mr Eastman set out his grievances.

The court has heard he had resigned in 1977 and later took an invalidity pension.

But Mr Eastman believed he was pressured to leave the treasury department. He said he was under immense pressure, and staff were “hypercritical” of him when he made the odd mistake.

The flow of work to him slowed to a dribble, he said.

He said the department had, with "deliberate negligence", failed to counsel him against resigning, and if it had he would have “withdrawn my heat of the moment resignation”.

He believed he would have taken his sick leave and then transferred to another department.

The trial's first witness, who prosecutors called to give evidence after lunch, was a senior official at the office of the Commissioner of Superannuation who often dealt with Mr Eastman following his resignation.

"Mr Eastman's policy was to try and go as far to the top in the office as he could when he had a complaint," the witness Ronald Whithear told the court.

Mr Whithear was questioned about Mr Eastman's election for a lump sum payment rather than a pension following his resignation, and then his battle to have the election withdrawn.

The Administrative Appeals Tribunal eventually found in Mr Eastman's favour, the court heard, and allowed him to apply to have the election withdrawn.

Defence barrister George Georgiou SC suggested that if anything could be said about Mr Eastman it was that he was a very persistent man.

"The most persistent applicant I have ever met in 30 years," Mr Whithear replied.

He said Mr Eastman was declared fit to return to work, with conditions, in December 1988.

The conditions included that Mr Eastman worked on "self-paced" projects and had limited contact with other people.

Those conditions were "almost unique", Mr Whithear said.

He was not aware of any job offer to Mr Eastman that would have accommodated those conditions.

Janne Graham, then honorable secretary of the Superannuation Association, said under cross-examination that Mr Eastman told her he was pleased to receive news he was deemed fit to return.

He felt he was ahead and that he had won, Ms Graham told the trial.

The trial continues on Monday.