Contract killer Stephen John Asling, who murdered Melbourne gangland figure Graham "The Munster" Kinniburgh on the orders of Carl Williams, has been sentenced to life in prison with a minimum term of 27 years.

Mr Kinniburgh, 62, was gunned down by Asling, 56, as he got out of his car in the driveway of his home in Kew, in Melbourne's east, 13 years ago.

Judge Stephen Kaye called the killing "cold-blooded and heartless."

It was one of the last unsolved murders committed during the more-than-decade-long underground drug war in which more than 30 people were killed.

Asling carried out the hit with Terrence Blewitt under drug kingpin Williams' instruction.

Both of those men are now dead.

Williams was murdered in prison in 2010, while Blewitt disappeared in suspicious circumstances just a year after Kinniburgh's murder.

His remains were found at a vacant block in Melbourne last year.

The Supreme Court was told Asling and Blewitt had initially been contracted to kill a Williams rival, crime patriarch Lewis Moran.

But after trying to kill Moran for several months without success, Williams told the men to instead target Kinniburgh, who was one of his close associates.

The pair had lain in wait for the gangland figure to return home on the night he was murdered.

Carl Williams hired Asling to kill Lewis Moran and Graham Kinniburgh. ( ABC News )

Murdered for 'base' motives

Prosecutors previously told the trial Asling had acted as a decoy, yelling "oi dog" at Kinniburgh as he got out of his car.

Kinniburgh was killed on the instructions of Carl Williams. ( ABC TV )

Kinniburgh shot in Asling's direction before Blewitt jumped from the bushes and fired three shots including one to the head.

Asling maintains his innocence.

Judge Kaye said the murder had been planned for about four months.

"Graham Kinniburgh gave you no cause or reason to have any grievance against him, let alone kill him," he said.

"Rather, you and Blewitt killed him for the most base of human motives, namely for reward.

Judge Kaye said the "amoral nature" of the killing was highlighted by the "casual manner" in which the decision was made to substitute Kinniburgh for Lewis Moran.

"The concept of contract killing is utterly abhorrent to the fundamental values of a civilised and decent society," he said in his sentencing remarks.

He said Kinniburgh was "totally vulnerable" and "defenceless" when he was gunned down outside his family home.

"Your murder of him was brutal, callous and utterly cowardly."

Asling will serve a minimum term of 27 years.