Ivan Milat could die within weeks. Here are 14 unsolved cases he's been linked to.

Update: Serial killer Ivan Milat has been transferred to the Intensive Care Unit of Sydney’s Prince of Wales Hospital. Milat was diagnosed with terminal oesophagus and stomach cancer in May and given three months to live.

Serial killer Ivan Milat killed seven young backpackers between 1989 and 1993. In 1996, he was sentenced to life in prison without the prospect of release.

He is now 74, and has been diagnosed with terminal cancer.

Milat is dying from oesophagus and stomach cancer and in his last weeks left on this earth, he is being urged to do one thing.

Confess.

But not just to the seven murders he was convicted for but never admitted to,  he is also being urged to confess, if guilty, to the dozens of cases that he has been linked to over the years that bear similarities to his murders.

Here is the trailer to Catching Milat. Post continues after video.

For the families of Caroline Clarke, 21, Joanne Walters, 22, James Gibson, 19, Deborah Everest, 19, Simone Schmidl, 21, Gabor Neugebauer, 21,  and Anja Habschield, 20, their loved ones killer will most probably die without ever admitting to their brutal rape, torture and murder.

NSW Police Minister David Elliott is leading the charge demanding Milat "do one last honourable thing on his deathbed".

In 1993, NSW homicide detectives launched a nationwide probe into murdered and missing young people in every state and territory in Australia.

The list was 58 people long, and Milat was considered in many of the cases.

The bodies of Milat's known victims were found face down in shallow graves in the Belanglo State Forest between Canberra and Sydney, with twigs and branches covering their bodies.

One of his known weapons was a .22 calibre shotgun, he wore a wide brimmed hat, and he picked up his victims while they were hitchhiking.

Beer bottles were often left at the scenes of his crimes, and his female victims usually had no pants or underwear on.

Here are some of the stories that share similarities:

Keren, 1971.

In February 1971, Keren Rowland and her sister were travelling in separate cars on their way to a hotel in Canberra.

But Keren never arrived, and her car was found later that night in a rugged area on the outskirts of town.

At work the next day, Milat apparently boasted to his workmates about killing a man and burying the body in the bush.

Three months later, Keren's remains were found 15 metres off a track in the Fairburn Pine Plantation near Canberra.

She was found lying on her back, with her arms above her head and her clothing pulled down.

There was also a beer bottle near her head.

20 years later, the crime scene was compared to those in the Belanglo State Forest.

Her case has never been solved.

Robyn and Anita, 1972.

Robyn Hoinville-Bartram, 19,  and Anita Cunningham, 18, were student nurses and flatmates, and set off from Melbourne in June 1972 with a plan to hitchhike to Queensland.

Robyn's body was found under a bridge 80kms west of Charters Towers, which is inland from Townsville.

She'd been shot in the head by a .22 calibre rifle, which is the same weapon used by Ivan Milat, and was naked from the waist down.

Anita was never found.

Police examined Milat's movements around the time of the disappearances - but never officially linked him.

Gabrielle and Michelle, 1972.

Best friends Gabrielle Jahnke, 18, and Michelle Riley, 16, decided to hitchhike from Brisbane to the Gold Coast to check out the nightlife in the October of 1972.

A week after their disappearance, Gabrielle's body was found at the bottom of a steep embankment on the Pacific Highway, halfway between the two destinations.

Michelle's body was found 10 days later in bushland. She wasn't wearing underpants and her dress had been pulled up.

Branches had been arranged over her body.

Again, the crime scene showed similarities to Milat's murder scenes.

Amanda, Leanne and Robyn, 1978.

Amanda Robinson, 14, Leanne Goodall, 20, and Robyn Hickie, 18, all disappeared while waiting at bus stops between December 30, 1978, and April 21, 1979.

They lived in the Eastlakes district on the New South Wales Central Coast, and were all snatched at night while alone.

The three women had never met, but their cases were near identical.

Leanne was last seen at Newcastle's Star Hotel. Robyn was last seen walking on the Pacific Highway after meeting a friend at the Belmont hotel, and Amanda was also last seen on the Pacific Highway on her way home to Swansea.

The main suspect at the time was Ivan Milat.

In the late 70s, Milat was a roadworker in the area, and stayed at hotels in the surrounding suburbs (including the Star and Belmont Hotel) in the months the girls went missing.

Though Milat attended an inquest into their deaths, he offered nothing to help investigators and denied having known the women or ever having picked up a hitchhiker in that area.

“I can look these mothers in the eye and tell them I wouldn’t do that sort of thing to anybody,” the country’s worst serial killer told the girl's mothers from the dock.

Milat was quoted as making comments during the inquest like; "I could ask how could they let a 14-year-old [Amanda Robinson] run around at midnight?"

Gillian and Deborah, 1980.

Gillian Jamieson and Deborah Balken, both 20, were trainee nurses and close friends, and had been known to hitchhike.

On an evening in June 1980, they were seen talking to a man with a large-brimmed black cowboy hat at a pub in Parramatta, Sydney.

Later on, Deborah called her flatmate and said the pair were getting a lift to a party in Wollongong on the South Coast.

After their disappearance, Milat, who that year had been working in Western Sydney, is understood to have been interviewed and was named as a person of interest during an inquest into the girl's death.

Elaine and Kerry Anne, 1980.

Elaine Johnson, 17, and Kerry Anne Joel, 18, were last seen in Cronulla, Sydney, in late 1979 or early 1980.

It's thought they hitchhiked to Wyong on the Central Coast, and ran into foul play.

The main suspect at the time of their disappearance was also Ivan Milat  - who had been working in the area they are believed to have been headed to.

Peter, 1987.

In November 1987, Peter Letcher left the southwestern Sydney suburb of Busby to hitchhike to his parent's home in Bathurst, but he never arrived.

Two months later, some bushwalkers discovered his remains on a forest trail near the tourist attraction the Jenolan Caves.

He was lying face down in a shallow ditch covered in branches and leaf litter.

He was bound, stabbed multiple times in the back, and shot five times in the head from a .22 calibre weapon.

Dianne, 1991.

Dianne Pennacchio, 29, told a friend after a night out at a hotel in Bungendore in September 1991, she was going to hitchhike the 20 minute drive home to Queanbeyan, which is just outside Canberra.

She was last seen walking towards the Kings Highway.

Her body was found two months later lying face down and covered in pine branches in the Tallaganda State Forest south west of Canberra.

Her underwear was around her ankles and she'd been stabbed in the vertebrae. One of Milat's known victims was paralysed by stab wounds to her spine.