A skeleton found in a Melbourne landfill is likely to be the remains of Terrence Blewitt, a career criminal accused of an unsolved Sydney murder but never charged.

Victorian detectives leading an excavation on a site in the north Melbourne suburb of Thomastown found the remains late on Wednesday. They believe Blewitt, 53, missing since 2004, may have been killed in a hit ordered by the now dead drug kingpin Carl Williams.

In 2014, a man claiming to be Blewitt's former partner in crime blamed him for the 1995 murder of Sydney security guard Robert Jones.

Mr Jones was gunned down outside the Westpac bank in Miranda in Sydney's south. A 2009 inquest found "an unknown person shot him during the course of an attempted armed hold-up".

Blewitt had specialised in armed hold-ups in the 1980s, spending time in jail for one. He had threatened a Coffs Harbour couple at gunpoint as part of a home invasion in 1994.

The alleged accomplice in the Miranda job, known as Mr X, told the Herald he had been Blewitt's getaway driver.

"I struck a cowboy, I had to put one in him," Blewitt allegedly told Mr X after the botched robbery, still smelling of gunpowder.

Mr X said he had made detailed confessions to the NSW Crime Commission about Blewitt's involvement in 2000. He also said he had implicated Blewitt in an induced statement to a detective from the NSW Police Special Crime and Internal Affairs.

"They had admissions, I was there on the day when a bloke is murdered in the street, it was pretty heavy shit at the time," Mr X said. "It amazes me it only went as far as it did."

Blewitt was neither charged nor arrested. He was sentenced in 2000 for a minimum of three years' jail for conspiracy to commit an armed robbery, then released shortly before the murder that may have been his downfall.

Victorian police believe Blewitt was part of a group that killed organised crime figure Graham 'The Munster' Kinniburgh in 2003. Kinniburgh, 63, had been implicated by a coroner in the 1998 death of Alphonse Gangitano, an early fatality in the Melbourne gangland killings. Carl Williams, a key figure in those killings, was murdered in Barwon prison in 2010.

Police are yet to formally identify the bones found at Thomastown using dental records but believe they belong to Blewitt.

A NSW police spokesperson said they were unable to comment.