In letters to a suburban Melbourne magistrate between 2010 and 2013, Donohue's doctor claimed the tumour progressed to terminal and his patient entered palliative care.

His court case for dishonesty offences was adjourned repeatedly and the magistrate was told they'd receive a death certificate when the time came.

But such a certificate never arrived because Donohue wasn't in palliative care and he didn't have a brain tumour.

The now 66-year-old just didn't want to face court.

County Court Judge John Carmody on Tuesday jailed Donohue for four years and five months for creating false documents, attempting to pervert the course of justice and perjury.

When he was caught out and interviewed in 2014, Donohue lied and claimed the documents had been obtained and sent to the court by his employer, the Australian Signals Directorate.

When the documents were discovered on his computer, he said the details contained were true but he couldn't reveal the name of his real treating doctor, or the name he used for treatment, because it was a matter of national security.

Another lie.

Donohue signed documents in 2014 and 2015 saying he would be unable to appear because he was needed on urgent and special military duty and was required interstate on federal government duties.

More untruths.

He hasn't served in the defence force since a stint between 1970 and 1976.

"It was a fiction created by you so all your court matters ... would not be finalised," Judge Carmody said.

Donohue's lies were "persistent and brazen in nature", he added.

Donohue's dishonesty offending dates back more than 30 years and includes a period spent pretending to be a decorated major general who served in Vietnam.

He was convicted of 19 charges at a fourth trial earlier this year, after three earlier attempts were discharged.

Donohue, a married father of three, will be eligible for parole after serving two years and nine months in prison.

Australian Associated Press