Twenty three years ago, Melbourne schoolgirl Cherie Westell went missing after attending a suburban dental appointment in the middle of the day, ringing from a public telephone box to say she was about to catch a train home to Ringwood.

She was 15 years old. She has been missing since December 12, 2000.

In the Nine Network’s new eight-part series, Missing Persons Investigation, state police) with the support of the Australian Federal Police National Missing Persons Co-ordination Centre) take us inside 16 investigations involving misadventure, murder and in Cherie’s case, a deep dive into a disappearance without a trace.

“Cherie was a young girl who had been in the foster care system … she was taken to the dentist in Wantirna, dropped there and was making her way home,” Senior Sergeant Tony Combridge, of Victoria’s Missing Persons Squad, tells The New Daily.

“This is genuinely a mystery.

“Often times when we take on a case, we’ve got a fair idea of the scenario. Cherie has effectively left the dentist. After that we don’t know what happens to her, who she meets, what has occurred. We don’t know anything about what happens to Cherie after that.”

Senior Sergeant Combridge, 53, who has been a serving member in the force for 33 years, says if he and his dedicated squad could “solve one job today”, and it was the cold case of Cherie Westell, he would leave a happy man.

Heartbreak and happiness go hand in hand in this job.

“When we get good news, it’s a great job … but when you’ve got to deliver the worst news you possibly can, it is a really conflicting job because you’re providing some level of comfort through providing answers, [but] you’re still not telling people what they want to hear.

“Our entire reason for being here is that we investigate missing persons where homicide is the probable causation of them being missing … or unidentified remains where homicide is the probable cause for them being deceased.

“We are looking for those jobs where, it’s not like searching for a needle in a haystack, it’s like searching for a needle in a stack of needles. We are looking through all the missing persons reports and trying to find the ones that might be a homicide.”

Cherie Westell was a normal teenager who loved horses, sport, art and music, according to police. Photo: Victoria Police

‘Living with secrets’

More than 50,000 people go missing in Australia every year – that’s one person every eight minutes.

Most are found, reunited with relatives and a few, as in the show’s first episode, disappear like young Sydney woman, Kathleen, who vanishes off a busy street (she is eventually identified and traced through CCTV, but to this day her location is unknown and her case remains open).

At the time of Cherie’s disappearance just before her 16th birthday, she was a ward of the state.

Her previous foster mother, Frances, tried to make a police report immediately but was told a biological family member was required for that to occur, according to a Victoria Police statement in December.

As a result, the missing persons report was not filed until six days later.

CCTV of missing Sydney teenager Kathleen, who reportedly changed her appearance, emptied her bank accounts and most likely did not want to be found. Photo: Nine

A coronial inquest occurred in 2003, with the coroner finding that Cherie has most likely died.

“Never underestimate the power of being able to provide some level of certainty to a family,” says Senior Sergeant Combridge, adding that if Cherie had decided to vanish of her own accord, the police would have found a trace.

“But we have found nothing after that day, no contact with anybody. That says to me she has not been in contact with anyone because she can’t.

“As missing persons case go, we have nothing. No CCTV, no phone movement, nothing to work with. There is a $1 million reward announced late last year and forms part of the episode.

“At any given time, we are one phone call away from solving these [cases]. We just need the right person to reach out to us.

“The passage of time, while it’s devastating to the family, and while it makes our job harder, it can work in our favour because friendships dissolve, allegiances change and before you know it, somebody you’ve confided in as a friend may not be a friend anymore.

“Those responsible for Cherie’s disappearance have had to live with this secret for over two decades … 23 years is a very long time to be looking over your shoulder.

“If there was one case to break open, this would be it.”

Sydney police in the search for Kathleen in episode one. Photo: Nine

‘Time is critical’

The series, narrated by Blue Heelers and Underbelly actor Caroline Craig, ticks through at a fast pace and follows real-time investigations on the run.

The earlier someone is reported missing, the sooner police can act.

Craig, 48, now living in New York City, tells TND playing a cop as her first gig out of school gave her a great appreciation of the job as she spent time with members of the force and even got to go to a firing range for target practice.

“They are the real heroes of the series and their tireless work, picking us up when we’re down, finding loved ones, piecing together the mysterious disappearances of people who the rest of society has given up for ghosts.

“Cops often get a bad rap in today’s media, but I reckon they’re the modern-day saints.

“We forget how much we need them. When we’re hurt or in danger or lost they’re always there, putting their own lives at risk to save us, working through the night and they’re bloody funny.”

Throughout the series, there was one investigation which stood out among the case load.

It was Kathleen’s.

“Her story is heartbreaking and compelling at the same time. I want to jump in there and find her. I think we all know what it is to feel isolated and misunderstood, but what she perhaps doesn’t know is how many people love and care for her.”

Missing Persons Investigation premieres on Nine and 9NOW on Monday, August 14 at 8.45pm