Belinda Peisley, 19, was last seen leaving Katoomba Hospital, west of Sydney, on September 26, 1998. Her remains have never been found.

For more than 13 years police attempted to uncover what had happened to the young woman, but found little solid evidence beyond the fact that, shortly before her disappearance, the mother-of-two had inherited a significant amount of money from her great uncle and had developed a heroin addiction.

But in late 2012, investigators uncovered new information suggesting the young woman may have been the victim of foul play within the group of young people she was spending time with, many of them drug users. An inquest into Ms Peisley's death was initiated and police began searching a large swath of bush land near Blackheath.

The inquest heard that a few days after her death, Ms Peisley's house was broken into by a number of her former friends and acquaintances, who later used her identification cards to sell items at a western Sydney pawn shop.

Two of the 19-year-old's former friends - Jeremy Douglas and Saxon Holdforth - became "persons of interest" at the inquest, with the scrutiny on their activities intensifying.

The inquest received evidence from multiple witnesses suggesting that Ms Peisley had been killed and thrown off one of the Blue Mountains' many cliff edges.

"Some of the things I have heard over the years is that Jeremy, Saxon and Olly [Peisley's former boyfriend Oliver Tipping] took her in a car and bashed her and left her somewhere,"  Kerren Fittler said in a handwritten statement to police.

"After they've left her they've come back and got her body and done some things to her before or after she was dead and chucked her over the cliff.

"I heard she was killed over drugs or she wouldn't give them what they wanted."

Mr Holdforth and Mr Douglas have steadfastly maintained their innocence at the inquest.

On Wednesday, counsel assisting the inquest, Phillip Strickland, SC, said the evidence relating to the exact manner and cause of the young woman's death was inconclusive, but that it did "point strongly to her death being the result of some sort of homicide or violence".

"Much of the hearing has been directed towards whether these persons of interest had knowledge of or direct involvement in the circumstances surrounding Belinda Peisley's death," he said.

"The evidence regarding these persons is inconclusive and not capable of convincing a jury that a known person committed an indictable offence."

Speaking after the hearing, Ms Peisley's aunt, Sharon Versace said she was "very, very disappointed" that charges would not be laid.

"At the end of the day, someone hurt Belinda but they're still out there living their life and they've taken hers," she said.

"I'll never give up, the detectives have come so far - I'm hoping that one day we'll get some good news. It won't bring Belinda back, but it will be a bit of justice for the family."

Deputy State Coroner Paul McMahon will hand down his formal findings next month.