Cheryl Fallick’s faint memories of her “little sis” Debbie have never strayed far from her heart.

The 63-year-old has been looking for her sibling and their mutual friend Gillian Jamieson — long considered two of Ivan Milat’s unknown victims — for almost 40 years.

And now that Australia’s most infamous serial killer is dying of oesophageal cancer and not expected to last a month, Ms Fallick has pleaded for Milat to “do the right thing” before he dies.

Camera Icon Deborah Balken, 19, went missing in 1980 with Gillian Jamieson after getting a lift to a party in Wollongong on the NSW South Coast. Credit: News Corp Australia

“If he has one ounce of good in him, at least for the benefit of the families who are left, please tell us what happened,” she told The Sunday Times from her small NSW hometown of Cargo.

“He’s got nothing to lose ... there are so many families out there who must be thinking whether he killed their loved ones or not ... he should just tell police what he knows and what he did, which would put so many parents and others at rest.”

Cheryl Fallick, nee Balken, has never been “at rest”.

Her relentless search for her sister began in 1980 and only in recent years has it gently waned, though she never misses an opportunity to ring a reporter, speak to the local radio station or contact cold-case detectives.

When we first met in October 1980, she had been travelling on a train between Sydney and Wollongong for weeks, sleeping where she could and stopping strangers on the street, showing photographs and asking whether they had seen them.

Debbie and Gillian hadn’t been seen or heard of for three months.

The pair were best mates, had gone to Cumberland High school in Sydney’s west and had passed their Higher School Certificate in the same year. They shared a house in suburban Dundas with another young woman, Sue Gilchrist, and a man named Peter Godfrey.

Gillian was the taller of the two 19-year-olds, had flowing dark brown hair that rolled over her shoulders, blue eyes that sparkled in a cherub’s face and a full smile, while Debbie, with her mousy hair and cheeky grin, was instantly endearing.

While both were at the beginning of promising careers as nurse’s aides — Gillian at Ryde District Hospital and Debbie at Oatlands Nursing Home — they were far from angels. They drank, smoked pot and were sexually active, but still regarded by family and friends as responsible young women.

Two of their favourite haunts were the working-class Tollway Hotel in Church Street, Parramatta, and the Family Hotel in Rydalmere. Sometimes they would hitch-hike between the two, working on the premise that if they were together, they would be OK.

Camera Icon Gillian Jamieson. Credit: News Corp Australia

On Tuesday, July 8, 1980, Gillian told friend Virginia Carroll that she was planning to go to a party in Wollongong that coming weekend, while Debbie told workmates she was thinking of hitching north to Newcastle for a party with a man named Steve.

That Saturday, housemate Sue Gilchrist, who was also a nurse’s aide, went to work at 6am and presumed both Debbie and Gillian were still asleep when she left the house.

When she got home around 7.15pm that day, the house was locked and in darkness. Two hours later, the phone rang. When she answered, she heard the four or five pips that in 1980 signalled the call was STD (long distance). It was Debbie.

“Hello, Wong (Sue Gilchrist’s nickname) it’s Debbie. Me and Jamo are in Wollongong,” she told her flat mate. Sue then asked Debbie whom she was with: “People that Gill used to work with ... that gardener fella,” she explained before asking Sue if she could ring in sick for them both.

“Can you ring my work tomorrow and Jamo’s work on Tuesday and we’ll see you Friday?” she said, before adding: “I’m running out of two bobs, I’ve got to go, bye”. It was a short, typical conversation of little note. It would be the last time anyone heard Debbie’s voice.

Sue dutifully rang their respective employers and lied about the teenagers being sick on those specific, designated days.

Later that week, Sue went to the Tollgate Hotel and saw Mick Toomey, a regular drinker and an acquaintance of the three. She assumed Toomey was “the gardener fella” Debbie had referred to in the telephone conversation.

Toomey said he hadn’t “seen them for ages” and wandered off to play pool.

As it turned out, by “ages” Toomey meant the previous Saturday when Debbie was wearing a light blue sloppy joe and faded blue denim jeans, and Gillian brown jeans and a similar coloured light jumper at the pub. They were talking about a party. He would later tell police he believed the girls were waiting for someone to pick them up.

According to drinkers there, two other women around the same age, and some men had joined the girls. One of those men would leave a lasting, haunting impression on Carol Wall, a staffer who was serving at the pub’s snack bar that Saturday night.

Ms Wall was watching and listening to the group for no particular reason as she went about serving.

She remembered that the group in general and one man in particular were being very loud. Later, when Debbie and Gillian wandered over to order food at the counter, she again overheard them talk about a party in Wollongong. The dark-haired girl seemed less interested in going than her friend.

Then, according to Ms Wall, the loud man walked over and told them it would not be too far to drive them to the south coast city. After they ate their food at a nearby table, Ms Wall saw all three walk out.

She later told police the man was between 25 and 30, about six feet tall, of medium build, an Australian with olive skin, long black hair past his shoulders and was “very dirty”.

He had big hands, was wearing dark-coloured pants and a jacket and had a “terrible smell” about him.

And, she said, the man was wearing a black felt hat with a broad brim.

One of Sydney’s big-selling afternoon tabloids splashed with Ms Wall’s account of the mystery man in the black hat who detectives wanted to talk to about the now officially missing women. “Big Hunt for Man in Black Hat” screamed the page one headline.

Then a terrifying development. About three months later, Ms Wall was at work when three men came into the pub and stood near the snack counter where she was working. She naturally asked if she could help. The men didn’t answer for some time, before one of them turned to the others and said: “She doesn’t know.”

Confused, she looked at the group before eventually realising the tallest was the man who had been dining with the two missing nurses the night they vanished. It was the man in the black hat.

He had dramatically changed his appearance; gone was the hat, his long hair was now short and parted and its colour had changed with an orange/brown wash. He was wearing an open-neck shirt, Bogart pants and his hands were scrubbed clean.

But the menacing, dangerous demeanour was still lingering in his dark, deep-set eyes.

Camera Icon Australia’s most infamous serial killer Ivan Milat is dying of oesophageal cancer and not expected to last a month. Credit: Diimex

The hatless man then leaned over the counter and almost whispered as he looked directly at her: “She does know ... It was a terrible thing that happened. You know they’re dead. The police won’t find them. It’ll happen to your two sons and then you. I know where you live and I’m handy with a knife.”

He then hissed that he would cut her throat and slit her kids “from arsehole to breakfast”. He then calmly turned on his heels and walked out, with the other men trailing behind him.

The mother of two was stunned. She finished her shift in shock, went home that night and refused to step foot in the Tollway Hotel again. Her partner rang the publican the following day to say Ms Wall would not be back.

As months rolled into years and the disappearance slowly ebbed off the news pages, Cheryl refused to let her sister’s memory die. She never missed a chance to publicise missing persons week, talk to the local radio station, tell her story.

Then in 1992, a breakthrough. Ivan Milat, a road worker and gun lover with a penchant for knives, was arrested.

From an aggressive family dominated by cruel, boisterous men, Milat had serious criminal form going back to 1974 when he was charged but acquitted of the rape of two young women police claimed he kidnapped.

Milat was a cold-blooded sex predator, a psychopath with no remorse who preyed on vulnerable young people.

The evidence gathered against him by the largest number of detectives ever assembled was overwhelming on many levels.

The bodies of the seven dead — all young hitch-hikers, travellers and visitors who were either strangled, shot in the head, stabbed or, in one case, beheaded — were eventually found in two separate areas of the Belanglo State forest and pine plantation, south of Sydney.

But the gut feeling among many was that the belligerent, cocky road worker had many more victims to his credit.

Even one of Milat’s brothers, Boris, admitted that the most feared of his unpredictable, erratic siblings was “capable of extreme violence” and believed Ivan could have dispatched as many as 28 people to their grave.

Milat’s 1996 conviction, which brought to an end an exhausting 15-week trial, was also a defining moment in Cheryl’s relentless search, by then well into its second decade.

Milat had for years cruised the same highways Debbie and Gillian travelled. He worked with the Department of Main Roads in a depot not far from the Tollgate Hotel.

The pub also happened to be a well-known watering hole for many other DMR workers.

But the most haunting link was the photo police released of Milat wearing a black hat and cradling a shotgun.

In 2004, Detective Inspector Ian McNab, who was in charge of the cold case review, interviewed Milat at Goulburn Jail’s Supermax wing in regional NSW.

It was considered by most to be the last roll of the dice. Milat’s appeal to the High Court had been dismissed earlier that year, and with the then-60-year-old certain to die in prison, police were hoping Milat might shed light on it and other possible crimes.

No such luck. Milat was irritable and belligerent during the interview with McNab.

Every question thrown at him about Debbie and Gillian’s disappearance was dismissed with the trademark arrogance.

Camera Icon Cheryl Fallick with her grandchildren. Credit: Supplied

McNab’s statement to a 2006 coronial inquiry outlined in chronological order in which the numerous inquiries had unfolded over the years, and painted a picture of the task forces created, leads chased, databases endlessly searched, files reopened and triple-checked, witnesses questioned and re-interviewed.

McNab offered the coroner five possibilities of what may have happened: 1) the girls were lured from the Tollgate Hotel on the pretext of going to a party in Wollongong, and were kidnapped and murdered at an unknown time and location; 2) one of the girls may have died of a heroin overdose and those responsible for supplying the drugs may have murdered the second and disposed of both bodies; 3) both girls overdosed and their bodies were disposed of; 4) the girls were picked up while hitch-hiking either to or from somewhere, probably Wollongong, by a stranger and murdered, or; 5) they were killed by someone they knew who disposed of their bodies at an unknown time and location.

Both women were dead, he said.

In formally finding as much, Coroner Carl Milovanovich ominously added: “It is not even clear in this case whether the girls might have changed their minds and not travelled to Wollongong, but travelled north. We just simply do not know. There is just not enough evidence. It may well be that there is another serial killer out there and it may not be Ivan Milat.”

Meanwhile, Cheryl remains determined to find Debbie. She refuses to get a death certificate issued, despite it being clear that both Debbie and Gillian are dead, as the Coroner found 13 years ago.

Not surprisingly, she has no sympathy for Milat.

“I don’t feel sorry for him at all,” she says. “The sorrow he has brought to so many people ...’’

If Milat does not confess in his final days, Cheryl hopes someone may come forward to tell police something about what happened all those years ago.

“Someone knows something,” she says, before adding: “Debbie would have been 60 this year. I hate the fact that she’s still out there somewhere.”