Prosecutors have told the ACT Supreme Court David Eastman wanted to deliver "a harsh lesson for police" when he allegedly killed senior Australian Federal Police officer Colin Winchester in 1989.

Prosecutor Murugan Thangaraj told the jury the former assistant AFP commissioner pulled into the driveway next door to his Deakin house about 9:15pm on January 10, where he used to routinely leave his car because it made his elderly neighbour feel safer.

Mr Thangaraj said Mr Winchester had just opened the door of his car when he was shot twice, by what is believed to have been a Ruger 10/22 semi-automatic.

Mr Thangaraj told the jury Mr Eastman, now 73, was responsible.

"The Crown points to Mr Eastman as the man who fired those shots," he said.

The jury has already heard Mr Eastman was convicted of the crime but is facing a retrial because of flaws in the evidence.

Mr Thangaraj said he would present a case showing Mr Eastman's frustrations over his efforts to rejoin the public service and a looming case against him over an alleged assault of a neighbour were driving his state of mind.

"The Crown says the anger was building in Mr Eastman to murder someone in authority," he said.

Mr Eastman was convicted of the crime but is facing a retrial because of flaws in the evidence. ( ABC News: Ian Cutmore )

The Crown then detailed the events leading up to the murder, saying Mr Eastman had left his job in Treasury in 1977 voluntarily, but was "desperate to get back in".

He was later charged with assaulting his neighbour Andrew Russo, and the jury heard Mr Eastman was concerned a conviction of assault would put an end to his dreams of returning to the public sector.

The jury heard Mr Eastman's bid to dismiss the case made it all the way to Mr Winchester — the assistant commissioner of the AFP.

But the Crown prosecutor told the court that meeting "went very badly for Mr Eastman," as Mr Winchester refused to have the assault charges withdrawn.

Mr Eastman later allegedly told his GP he had been "virtually thrown out" of the room, saying "he wanted to get up and push the assistant commissioner off his chair".

He then allegedly said: "The police should be taught a lesson".

"[That] was not a comment, it was a threat," Mr Thangaraj said.

"It is the Crown case Mr Eastman did teach the police a very harsh lesson only four days later when he killed Mr Winchester."

The jury heard Mr Eastman received a letter from the AFP advising him it would not intervene in the assault case on January 10 — the same day Mr Winchester was murdered.

Mr Thangaraj told the jury Mr Eastman was motivated by revenge, allegedly telling his solicitor "I'll kill Winchester" and saying to someone else, "if it's the last thing I'll do, I'll get back at the police".

"The police, as far as Mr Eastman was concerned, were a very serious problem," Mr Thangaraj said.

Jury shown a gun bag allegedly containing Eastman's gun

The Crown also told the court Eastman had purchased a Ruger 10/22 — the same model as the gun used to kill Mr Winchester — a few months before the murder.

The jury heard Mr Eastman stored the rifle beside the Old Federal Highway, allegedly placing bottles of medication by it so he could find it later.

The court heard a passer-by found the rifle in a gun bag and handed it in to police, with five of the six bottles of medication nearby prescribed to Mr Eastman.

The rifle case was examined by the jury. ( ABC News: Ian Cutmore )

The jury was on Monday shown and allowed to pass around the gun bag, which the Crown alleged Mr Eastman obtained to keep the rifle in a good condition.

The Crown alleged that when he discovered his rifle had gone, Mr Eastman then purchased the same type of rifle from a man called Louis Klarenbeek in January 1989.

Mr Klarenbeek provided police with a cartridge from the gun, and the court heard forensics determined the same weapon fired both that cartridge, and the cartridges found at the scene.

However, the jury was told Mr Klarenbeek denied seeing Mr Eastman when he was shown photos of him.

The Crown alleged Mr Klarenbeek may have lied out of fear, or loyalty.

The gun used in the shooting has never been found.

Deceased witnesses' statements to be read to court

David Eastman (in beanie) was whisked straight from a van into court. ( ABC News: Ian Cutmore )

Mr Thangaraj said while some witnesses in the case had died, their statements would be read to the court from earlier proceedings.

The jury also heard the scale of the investigation "was the biggest police investigation in the history of the ACT and one of the biggest in the country" at the time.

He said the focus quickly shifted to Mr Eastman, who had not been able to account for his whereabouts, and had recently met Mr Winchester.

Mr Thangaraj raised the suggestion that some believed there was mafia involvement in the killing, saying that was implausible, and that it was Mr Eastman who killed Mr Winchester.

"The Crown says the mafia would not buy a gun from Queanbeyan that was advertised in the Canberra Times," he said.

He told the jury the prosecution's case would also include Mr Eastman's own mutterings to himself, recorded on listening devices police planted in his home.

Mr Thangaraj is expected to take more than a day to outline the case.