NSW Police have launched an investigation into four of the country 's most notorious serial killers in an effort to determine whether the men were responsible for more unsolved murders . The cold case review focuses on backpack murderer Ivan Milat , who was convicted of seven murder , along with Bandali Debs , Ashley Coulston , and Reginald Arthurell and other known mass murderers . Dozens of unsolved deaths are being re-opened and examined for links to the men by a review team from the NSW Unsolved Homicide Squad , a move which Inspector John Lehmann said was motivated by a desire for justice . The cold case review focuses on backpack murderer Ivan Milat , who was convicted of seven murders . 'Even though some of the murders are old , sometimes 30 years ago , and the killers are locked away it does n't mean we should give up , ' Inspector Lehmann told The Daily Telegraph . 'It 's about getting justice for the dead and for their families . ' The Unsolved Homicide Squad is currently investigating more than 600 unsolved murders which date back to 1965 . While official links between any of the known killers and their potential victims are yet to be made , Inspector Lehmann said he was hopeful that the task force would be able to build up enough evidence to charge the murderers . Inspector Lehmann said that while the review was 'routine ' , the approach was different , and made all the more unusual as a result of the reputation of the killers . Ivan Milat is considered by many to be Australia 's most notorious serial killer , responsible for the murders of seven backpackers whose bodies were discovered in the Bengalo State Forest in NSW . Milat is currently serving seven consecutive life sentences for the murders , including those of British backpackers Caroline Clarke and Joanne Walters , who were discovered in September 1992 after being reported missing in April . Ivan Milat is considered by many to be Australia 's most notorious serial killer , responsible for the murders of seven backpackers . Their bodies were discovered in the Bengalo State Forest in NSW in 1992 . British backpackers Caroline Clarke ( above , left ) and Joanne Walters , who were discovered in September 1992 after being reported missing in April . Clarke has been shot ten times in the head and Walters had been stabbed 35 times , and the bodies of his other victims , most of whom were foreign backpackers , also died of stab or gunshot wounds . Bandali Michael Debs is currently serving four consecutive life sentences for the murder of teenager Kristy Harty in 1997 , prostitute Donna Ann Hicks in 1995 , and police officers Sgt Gary Silk and Sen-Constable Rod Miller in 1998 . The judge presiding over the case called the murder of the teenager as 'entirely senseless , needless and wanton . ' 'This was , most clearly , a callous , craven and senseless murder in cold blood of an entirely innocent , defenceless and vulnerable young woman . The evidence leads to the inevitable conclusion that you murdered Kristy Harty for no other reason than for the sheer sake of it . ' 'You are an evil , violent and dangerous man , who places no value on the life of another , ' Justice Kaye said of the killings of Sgt Silk and Sen-Constable Miller . Ashley Coulston ( left ) is currently serving three consecutive sentences , and Reginald Arthurell ( right ) is a suspect in the unsolved murder of 82-year-old Catherine Mary Page . Bandali Michael Debs is currently serving four consecutive life sentences for the murder of a teenager , a prostitute , and two police officers . Bandali Debs was charged with the murder of prostitute Donna Ann Hicks ( above ) in 1995 . Debs is currently in the Goulburn Supermax Jail , along with fellow inmate Milat , who is suspected of killing more people than he is convicted of . Ashley Coulston is currently serving three consecutive sentences for the 1992 murders pf housemates Kerryn Hestridge , 22 , Anne Smerdon , 22 , and Peter Dempsey , 27 . In July of 1992 , Coulston responded to an ad placed by the housemates for a new tenant , and shot them in the back of the head execution style while they were hogtied in separate rooms of the house . Coulston is also a suspect in the Balaclava Killer case , where Queensland victims were raped and killed over a ten month time frame between 1979 and 1980 . Reginald Arthurell is a suspect in the unsolved murder of 82-year-old Catherine Mary Page , has pleaded guilty to manslaughter for the stabbing death of sailor Ross Browning , his ex-step father Thomas Thornton , and was found guilty of the murder of his fiancee Venet Raylee Mulhall . 'The team will look at what we have in ways of linking these murderers to a victim and then hopefully build up enough evidence to form a strike team and eventually charge them , ' Inspector Lehmann told The Daily Telegraph . Coulston is serving time for the 1992 murders of housemates Kerryn Hestridge , 22 , Anne Smerdon , 22 , ( above ) and Peter Dempsey , 27 .
NSW Unsolved Homicide Squad is investigating more then 600 cold cases . The review includes a focus on known serial killers such as Ivan Milat . In the past year there have been two murders in Sydney, one of which was committed by an unknown person who has not yet been identified.