Giving closing submissions in Kubilay Kilincer's murder trial on Thursday, crown prosecutor Brett Hatfield said jurors should reject the lies told by the accused when determining their verdict.
Kilincer, now 60, is accused of killing Mr Dastan in his western Sydney Esy Auto Dismantlers business on the morning of December 11, 1995. His body was found bashed underneath a vehicle in a pool of blood within the Blacktown premises.
Mr Hatfield said the mechanic had given inconsistent stories about his movements that morning to police and in court to cover up his crimes.
Giving evidence in the NSW Supreme Court, Kilincer said his boss had been angry with him when he arrived late to work on December 11 but had quickly calmed down.
In a prior interview with Detective John Mastrobattista however, the mechanic said Mr Dastan was drunk the morning he was killed and had lost money gambling at a Turkish cafe.
"You might think, members of the jury, it's patently false, it's patently false with what he said to Detective Mastrobattista … He completely contradicts himself in his evidence before you, sprinkling some Turkish words in there to give it some verisimilitude," said Mr Hatfield.
"Rather than acknowledging the lie for what it was, he sits here ... before you giving you patent falsehoods."
The prosecutor also took aim at the accused's wife Gulser Kilincer, saying she had lied about where her husband had gone the morning of the murder again to cover up what had happened.
This included Kilincer claiming he left his boss, who he says was then alive, early enough to buy bread as well as going to the Department of Social Security before arriving back at the wreckers to find media and police there.
Mrs Kulincer told the jury she had seen her partner come back home with a bag of bread.
"That detail that he came back home carrying some bread was false evidence given by both of them which they plainly, you might think, came up with falsely to assist the accused with his case," Mr Hatfield said.
Evidence from other witnesses described Esy Auto Dismantler's large roller doors being shuttered early on December 11 - which itself was unusual - and a worker blocking two people from entering the premises around 8 or 9am that day.
The deceased's wife, Sultan Dastan said she had called up Esy Auto Dismantlers that morning. Kilincer picked up the phone, saying that her husband was not in but that he would call back.
He never did.
"She said usually Kubilay would say 'have a good day, aunty' but this time he said 'bye bye' in a very strange voice and the call terminated," Mr Hatfield told the jury.
A metal pipe was shoved six centimetres into Mr Dastan's mouth and his severe head injuries were consistent with an attack using a bloodied sledgehammer that lay nearby.
Kilincer has pleaded not guilty to the murder.
The trial continues.
