Serial killers could be behind some of the state's backlog of unsolved murders and missing persons' cases, police believe.

NSW Police Homicide detectives are taking a different approach to 17 cold cases from the past four decades by re-evaluating how they could be linked to known serial killers such as Ivan Milat, Ashley Coulston, Bandali Debs and Reginald Arthurell.

Detective Chief Inspector John Lehmann of the NSW Unsolved Homicide Squad told the Daily Telegraph a squad had been formed to approach unsolved cases by starting with potential killers and cross-referencing their details and movements against potential victims.

"It's a bit of a departure from the normal way of investigating homicide. Normally you have a victim and then look for a killer," Inspector Lehmann told the newspaper.

"To us it's a routine review of unsolved homicides from a different angle," he said, adding that what was unusual about the approach was the "notoriety of those involved".

The detective highlighted the convicted killer Bandali Debs, 61, who is currently incarcerated in Goulburn's Supermax Jail for the murders four people — two Victorian policemen, Rod Miller and Gary Silks in 1998, Melbourne drifter Kristy Harty in 1997 and Sydney prostitute Donna Hicks in 1995.

All four of Debs' victims were shot, which gives police a framework for examining some of the cold cases.

"In the '60s Debs was living in Sydney when he had a dispute with a man walking his dog. He was only a teenager but armed," Det-Insp Lehmann said.

"He shot the dog and fired at the owner a number of times as he ran away. If he is capable of that kind of cold-blooded violence as a teenager it's a reasonable assumption someone like him is responsible for more."

Ivan Milat, Australia's most prolific serial killer, was convicted of killing seven young backpackers in the NSW Belanglo State Forest in the 1990s but it has long been suspected that he had more victims than those presently known.

Ashley Coulston was convicted for murdering three Melbourne students in 1992 but before that he spent the 1970s and '80s travelling up and down Australia's east coast.

He was the prime suspect in a number of rapes that occurred in Cronulla, south of Sydney, in the '80s and was known to have drifted as far north as Tweed Heads on the NSW-Queensland boarder.

Reginald Arthurell is currently incarcerated in Broken Hill for the 1995 murder of Venet Raylee Hall and two other manslaughters.

He is due for parole in two months after serving 18 years.

The other three convicted killers are serving life with no chance of parole.

The Unsolved Homicide Squad has more than 600 cases on its books going back over the past five decades.

Inspector Lehmann pointed out that the investigations into the unsolved murders were still only cursory and police were not yet linking any of the convicted killers to the crimes.

"We don't want to raise their hopes or bring up those emotions unless we have to," he said.