A new investigation will examine claims Australian serial killer Ivan Milat may have murdered dozens more young people over the course of decades before killing the seven backpackers whose bodies he dumped in Belanglo State Forest. 

The inquiry, which opens next month, will focus on at least 50 people aged from their late teens to their late twenties who were strangled, stabbed, shot or beaten to death, with Milat identified as the likely perpetrator.

It will examine a list of missing and murdered people from every Australian state and territory which, if proven to be linked to the so-called 'backpacker killer', would make him a more prolific serial killer than American monster Ted Bundy - or anyone else.

The list includes backpackers or tourists from the US, Italy, New Zealand, Germany and Britain, as well as Australians, whose bodies were dumped or whose remains were never found.

The murders stretch from the 1970s to the early 1990s - when Milat killed the three German, two British and two Australian travellers whose remains were found in shallow graves in Belanglo.

The parliamentary inquiry spearheaded by NSW Upper House MP Jeremy Buckingham will look into multiple cases of people who vanished while travelling in pairs, like six of the seven Belanglo deaths.

It will also investigate why Milat roamed free after skipping bail on a double rape in 1971 and his 1994 arrest.

'The issue for us is how, from the early 1970s to [the] Belanglo [murders], he was allowed to commit scores of abductions and opportunistic homicidal killings,' Mr Buckingham told the Daily Mail.

'He was recognised at crime scenes, in identikit images, and never questioned or arrested. Coroners found him to be the person of interest at inquests. 

'A man wearing a large black cowboy hat, which we know Ivan owned and loved to wear because we've seen the photos of him posing in one with his guns, was identified by witnesses in some cases.

'There was a man named "the cowboy killer" that was believed to have been Milat, and he was recognised - by a passing police officer - at the scene of a murder by a lone gunman. 

'He was acquitted of crimes his accomplices - one of them his brother - got 18 years for. He was never pursued for another crime until Belanglo, and that inquiry stalled until a citizen on his own found the second two sets of bodies.

'There was a task force called Fenwick before Task Force Air [the NSW Police task force established to investigate the Belanglo backpacker murders], which looked into 17 murders and failed to arrest or convict anyone, and it was only after a coroner slammed that [that] the NSW Police formed the Unsolved Homicide Unit.

'Why was one of the worst serial killers in Australia let loose when police had already identified him as probably responsible for these 50 murders?

'NSW Police were well aware of  the savagely brutal murders of beautiful women, sometimes in pairs, and then increasingly couples and men, and that they were connected to Milat.' 

Standing by a wall in his office at NSW Parliament House which is covered with photos, news articles, maps and the images of dead and missing, Mr Buckingham showed the Daily Mail a police photograph of Milat's 'kill kit'.

It consists of a selection of the gun-obsessed Milat's firearms, plus an array of knives, gags, spray bottles and a sinister hood made from a paintball mask with 'Die' inscribed on one cheek.

Detailing how Milat’s modus operandi evolved over time, Mr Buckingham described some of the most tragic cases: young women never to be seen again who wrote notes to loved ones, he believes, while they were restrained under threat of death.

'Why was this homicidal maniac not caught and locked up sooner?' he said.

'We can link these murders and the locations of bodies and places of disappearance to areas where Ivan was living or working.

'He frequented Kings Cross and I believe that the three couples he killed and dumped in Belanglo he met there, not hitchhiking out west on the Hume Highway.

'On one of the times he was in jail, on remand in Long Bay, he told his cellmate how when he was a roadworker on the Kings Cross tunnel, which was built from 1970 to 1975, he murdered dozens of young people.

'He dumped them, he told Noel Manning, around Heathcote and the Royal National Park.

'There are a number of sites that were never properly searched, which need to be looked into as Ivan's burial grounds.' 

The 'Inquiry into unsolved murders and long-term missing persons cases in NSW between 1965 and 2010' will investigate cases including: 

STEPHEN LAPHTHORNE &  MICHELLE POPE

Pymble, NSW. August 25, 1978

It was August 25, 1978, when Michelle Pope, 18, and Stephen Lapthorne, 20, left his home in West Pymble, Sydney, heading for her place in Berowra.

They were driving in Stephen's pride and joy, a rare lime green Bedford CF van, the 'Scooby Doo'-style vehicle which he had lovingly customised.

The 1977 car had a four-inch, dark green horizontal band along each side, chrome-plated mag wheels, and a 150cm aerial in the centre of the roof, with a clip-on aerial above the driver's window.

Inside the vehicle were high-back Ford Escort seats and black curtains across the rear windows.

The couple didn't turn up at Michelle's home, but a witness saw the vehicle at Gordon alongside two carloads of men.  

Days, months and years went by with no sign of the couple or the lime green Bedford.

In August 2005, a coronial inquest found Stephen and Michelle had died.

Milat, who was working around northern Sydney at the time of the disappearance, was named as the person most likely to have killed the couple, but the coroner handed down an open finding as to the date, time and cause of death.

It has since emerged that Milat loved lime green cars - he once owned a lime green Valiant. And then, in 2017, a burnt-out Bedford was found in the NSW bush.

Traces of lime green paint were identified and it had the bucket seats and customised items. The vehicle's engine number was the same, bar one digit, from the one Lapthorne had registered.

The location of the van was 50km south of the Belanglo Forest.

ANNA ROSA LIVA

Coober Pedy, South Australia. November 28, 1971

Anna Rosa Liva, who came from Pordenone, in northern Italy, arrived on a bus at Coober Pedy from Alice Springs at 10pm on November 27, 1971.

She was one of many foreign backpackers who had arrived to explore the Outback town, and was booked into a well-known budget motel just off the main thoroughfare.

At 8am the next day, Anna ate breakfast at the Last Resort Cafe and walked the few hundred metres back to her accommodation, had a cup of coffee, and told staff she was going opal hunting.

She used the words 'noodling for opals', which the staff believed she must have picked up from a local. She was last seen at 11.30am around the town's council chambers.

Police believe it is most likely that she had a discussion with someone and went willingly with her killer.

Her body is believed to have been disposed of in one of the thousands of disused mineshafts that surround the town.

The inquiry will look into possible links between Anna Rosa and the Belanglo victims Gabor Neugebauer and Anja Habschied, who just two days before she vanished had been at Uluru.

After the German couple had arrived in Australia, they are believed to have travelled swiftly through the Outback, possibly riding with the same person who eventually dropped them in Sydney.

Gabor and Anja were last seen alive on Bondi Beach on Christmas Day 1991, and there is growing evidence Milat's hunting ground for backpackers was Kings Cross, where most stayed while in Sydney.

In November 1993, their bodies were found in Belanglo. Habschied was headless and Neugebauer had been shot in the head six times.

TONI CAVANAGH & KAY DOCHERTY

Warilla, near Wollongong, NSW. July 27, 1979

Kay Docherty, 16, told her parents she was staying at her best friend Toni Cavanagh's house. Toni told her family they were going to the movies with Kay's aunt and uncle.

It was July 1979, and, in reality, the two teens were on their way to the Wollongong CBD to attend a disco on the evening of the 27th.

Their last sighting was at a bus stop at dusk.

The following week, Toni and Kay's families received separate letters from the pair posted from the Kings Cross area, saying they were staying with friends and would be home soon.

The handwriting was theirs, but in Kay's letter there was a misspelling - 'write' instead of right - which troubled her family because she was a bright and diligent student, good at English.

'Dear Mum & Da,' the note reads, 'I have gone away with a few friends to Sydney. I will be back in a week. I am all write so don't worry about me. Love Kay. P.S. I love you both very much.'

In 2009, police issued a $100,000 cash reward, saying: 'Their families have spent the last 30 years wondering what happened to their daughters. They deserve closure.'

GILLIAN JAMIESON & DEBORAH BALKEN

Tollgate Hotel, Parramatta, 12 July, 1980

Twenty-year-old high school friends Deborah Balken and Gillian Jamieson were drinking on the evening of July 12, 1980, at Parramatta's Tollgate Hotel, where they were seen chatting to a man wearing a large-brimmed black cowboy hat.

From Cumberland, western Sydney, they were believed to have left the hotel about 7pm.

At about 9.15pm, Deborah phoned a friend to say they were getting a lift to a party in Wollongong.

During the conversation, Deborah said they were with a former workmate of Gillian, whom she described as being 'the gardener fellow.'

Their bodies were never found.

Milat was known to drink at the Tollgate. At the time of the suspected murders of Jamieson and Balken, he was working at the Granville depot of the then Department of Main Roads.

PETER LETCHER

Busby, Sydney NSW. November 13, 1987

Peter Letcher had no money and no job, and on a Friday in November 1987, the flat-broke 18-year-old was in need of a lift to Bathurst from Sydney.

The unemployed sawmiller had travelled to Sydney to propose to his 15-year-old girlfriend. She told him she was too young to get married.

Letcher, who had lost his job at a timber mill two years earlier, left Busby in the city's south-west, saying he intended to hitchhike back home. 

But he never made it home, and it wasn't until the following year that his remains were found in the Jenolan State Forest, west of Sydney.

He had been stabbed and then shot, execution-style, five times in the head, and his was body covered with branches. 

Milat was employed by the Department of Main Roads at the time in that area.

The late Clive Small, the former Task Force Air Commander, believed this was the most likely of the unsolved murders to be Milat's doing.

'When you look at the way he was murdered, shot in the head and stabbed in the back - that's the way many of the backpackers were murdered,' he said.

'Ivan was also known to be in the area at the time, and Peter's body was also left in a bush area in a similar way to the others, but there wasn't quite enough evidence to charge him.'