Were Elaine Johnson and Kerry Anne Joel killed by Ivan Milat?

Backpacker murderer Ivan Milat may have something to do with the disappearance of two teens in 1980. Photo / AP

Two teens were walking up a quiet road, thumbs stuck out over the bitumen, looking for a lift.

They were hitchhiking to the Central Coast and it was the 80s and hitting the open road with strangers was common and considered safe.

Any story of hitchhiking these days could end in a horror movie, but 30 years ago it was just another mode of transport.

But for two young women, it appears the person who picked them up was not somebody just heading their way, but instead a psycho killer with a sadistic desire to cause pain.

Cronulla girls Kerry Anne Joel, 18, and Elaine Johnson, 17, were believed to be hitchhiking to the Central Coast when they disappeared on February 1, 1980.

Some of Ivan Milat's victims were found in the Belanglo State Forest. Photo / Adam Taylor, News Corp Australia

They have not been seen since they left Cronulla 36 years ago.

But now an inquest into the disappearance of the two teens has suggested they may have had a run-in with notorious backpacker murderer Ivan Milat.

The Daily Telegraph reports Detective Senior Constable Richard McNally said the teens' missing person case was similar to other disappearances in the 80s and 90s.

Milat was found guilty of causing those comparable disappearances.

According to the Ivan Milat Biography, the backpacker murderer was jailed in 1971 after being charged with the abduction of two women and the rape of one of them.

Charges against him were later dropped.

In 1996 he was found guilty of seven backpacker murders and was jailed for life.

Many of his victims were found in the Belanglo State Forest, 140km southwest of Sydney.

Kerry's mother Judy Rose has never been able to get over her daughter's mysterious disappearance.

She told Fairfax Media whenever she heard about somebody being dug up in the bush, she wondered if it was her daughter.

"The only way to cope is to put it out of your mind," she said.

Kerry had a job at a supermarket and went to Woolloware High School.

Her friend Elaine attended Cronulla High.

Rose told Fairfax Media her daughter was popular and had a cheeky personality.

Ivan Milat was found guilty of at least seven deaths. Photo / News Corp Australia

"Kerry had a boyfriend, Robert, and she didn't take any of her possessions," she said of the day she disappeared.

"She had a lot of friends and what scares me is that no one has been in contact with her."

On the Australian Missing Persons Register Facebook page, Kerry's friend Ann-Maree Carr spoke of how the disappearance affected her.

"Kerry was my best friend and her disappearance has affected my life to this day and will until the day I die," she said.

"Not a day goes by without her in my thoughts.

"I hold so much guilt because it should have been me with her [the day Kerry went missing]."

On Tuesday, a coroner told Kerry's mother her daughter and Elaine had probably met with foul play and was dead.

"I'm so, so sorry," deputy state coroner Mary Jerram said before telling family members the cases would be referred to the homicide squad.

"I think we have to assume there must have been foul play."

The inquest at the State Coroner's Court in Glebe heard the age of the case made it extremely difficult for police to put exact dates on the last sightings of the young women.

A friend said she last saw the pair in what she thought was 1979, on the day Kerry crashed her mother's car and left it in the garage.

The friend said she went to an arcade with the girls but left them to walk home.

The girls were among a large group who went missing in NSW in the late 1970s and 1980s, the inquest heard.

According to Australian Associated Press, Kerry, who may have been pregnant, was known to hitchhike as far afield as Wyong on the NSW Central Coast.

"Around that area I think 14 girls went missing," McNally, the officer in charge of the latest investigation into the missing girls, told the inquest.

"I think every time they were hitchhiking they were running the gauntlet."

The court heard the girls often spent long periods at friends' homes and were not immediately reported missing.

Ivan Milat in 1983, holding World War One vintage machinegun. Photo / News Corp Australia

There have been reported sightings since their disappearance, with some suggestions they were seen in 1982.

There were also reports the girls were seen in Kings Cross after they went missing.

Possible sightings could never be confirmed.

Jerram said it was extremely unlikely people so young would have the resources or inclination to start a life under a new identity.

Even if they had, the women, who would now be in their 50s, would eventually seek out their loving families, she said.

Outside court an emotional Rose showed reporters a photo she carried of her daughter.

She said things may have been different if previous investigators had been as thorough as McNally had been.

"It's the first time in all these years I've felt somebody really, really was looking for Kerry," she said.

"Police should have done this in the first instance."

Family members in the court said "yes" and one clapped as Jerram said she would refer the cases to homicide police.

- Additional reporting: AAP