It is a cruel story: a young man on the brink of adulthood having the time of his life, travelling the globe before starting university, the world at his feet in every sense.

And then he was gone.

This weekend marks six months since 19-year-old Belgian backpacker Theo Hayez disappeared after a night out in Byron Bay.

He was last seen leaving the Cheeky Monkeys bar about 11:00pm on May 31 and his phone last "pinged" in the Cape Byron area, near the lighthouse early on June 1.

Despite an extensive land and sea search and a groundswell of support from the local community, the family is still no closer to any answers.

Theo's godfather, Jean-Philippe Pector, speaking on behalf of the family, described the anguish they continue to endure.

"It is a mix of very deep sadness and emptiness, not only induced by our loss but also by the fact of not knowing what happened to Theo," he says.

"It is an exhausting torture."

Laurent Hayez with Jean-Philippe Pector (L) and Theo's cousin Lisa Hayez (R) at a press conference in June. ( AAP: Regi Varghese )

He says they were living an "emotional rollercoaster" amid the ebb and flow of elements of hope, saying it "generates a mental stress and fatigue which doesn't seem possible to escape".

The army of volunteers in Byron and beyond who continue to search for Theo and maintain momentum through the Facebook page Looking for Theo Hayez had given the family strength, he said.

"Their ongoing dedication to help us, and the amount of work we manage to do together to give us a maximum chance of finding information, is incredible," Mr Pector says.

The Theo Hayez story has engaged people for many reasons.

There are the images of his cherubic, smiling face.

There's the incongruity of a horror tale coming out of the paradise of Byron Bay.

Then there was the heart-wrenching appeal by Theo's father Laurent for information and his promise to Theo's little brother, Lucas, that he would bring the missing son home.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 9 seconds 1 m 9 s Father of missing backpacker calls on WhatsApp to release messages

Reaching out for help

Among those supporting the Hayez family is Loren O'Keeffe, founder of the Missing Persons Advocacy Network, which offers practical resources for families over the short and long term.

Her own brother, Dan, went missing aged 24 from the family home in Geelong in 2011. Tragically his remains were found in 2016, but his memory lives on in Loren's work.

Loren O'Keeffe has been working with the Hayez family. ( ABC News: Geoff Kemp )

She set up MPAN in 2013, after her public search campaign for Dan — who wasn't deemed a "high-risk" case by police because there were no suspicious circumstances — drew interest from other families of missing persons who asked her for practical advice.

"It's absurd that in this day and age where you have YouTube tutorials on how to put on mascara, how to boil an egg, there was no guidance of what to do when you find yourself in this unimaginable situation where your loved one has vanished," Ms O'Keeffe says.

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A hurdle for families which can be distressing, she says, is the gap in expectations about what the police can do.

She said until it happened to her family, missing persons was something she only knew about from TV shows and movies where there is a "pretty intensive investigation" with multiple resources.

"And that is not at all realistic," she says.

"I think it's really important that's made a lot clearer initially that families know what to expect from police because it is really heartbreaking when you find, like we did, that the police weren't able to allocate any resources to us because Dan's case wasn't high risk."

Geelong man Daniel O'Keeffe went missing in 2011. ( Facebook: Dan Come home )

MPAN is run singlehandedly by Ms O'Keefe and is funded entirely by donations.

It's currently working with about 60 families and offers tools such as a timeframe and checklist of things to do, contact details for media outlets, hospitals, and homeless services, and templates for posters and media releases.

The over-arching resource, its online Missing Persons Guide, has been accessed by more than 70,000 people worldwide.

Now MPAN is taking on a new level of work in providing emotional support, and a focus on "acknowledging the very unique and very traumatic type of loss that families are experiencing".

"Naturally when someone disappears, it's all about the missing loved one," she says.

"But in the longer-term if they remain missing, the plight of families and friends that are left behind, just kind of fade into obscurity. People don't think about them, they don't have a voice."

MPAN has this month launched a new campaign, "Missed Birthdays", which urges ongoing support for families, and next year will launch a pilot program offering specialised training for counsellors.

Naming the loss

In the most recent research from the Australian Institute of Criminology, over 2008-2015 there was an average of 38,159 missing persons reports every year.

In 2015, there were 40,580 missing persons, an increase of 12 per cent since 2005-06.

Ninety-eight per cent of people are found alive, but research says each case directly impacts at least 12 people.

A conservative estimate by researchers is that at least 250,000 people are affected each year.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 55 seconds 55 s CCTV footage of missing backpacker Theo Hayez wearing a baseball cap

Support for families of missing persons in Australia is still in its formative stages, however. The police aren't traditionally employed to provide emotional support — and access to networks is limited.

In NSW, there's the Friends and Families of Missing Persons Unit which has been operating since 2000 and offers counselling services and other assistance and dealt with 14 referrals over the past financial year.

In counselling work with missing persons' families, there's a specific term coined for the unique experience: ambiguous loss.

This term was first used by US academic Pauline Boss in 1999 and although clunky and vague, goes someway to define the indefinable.

Ms O'Keeffe says it's a grief that, unlike traditional bereavement, is never resolved.

"Research has found that there's no other form of loss that is as unmanageable and traumatising as the stress of ambiguous loss," she says.

"We are creatures that need answers to things."

'We don't want to give up hope'

Dr Sarah Wayland, from the faculty of Health Sciences from the University of Sydney, is one of Australia's leading researchers into missing persons families and will be overseeing MPAN's counselling pilot program next year.

She has been working with more than 500 families of missing persons since 2004, first as a counsellor and then as a researcher.

She produced a new guide for the Australian Federal Police in March, called Acknowledging the Empty Space, which is a resource for the police, counsellors, families and health services about dealing with those left behind.

"People look absolutely haunted," she says of talking to families. "It's almost as if they've been holding their breath for significant moments in time.

"It's a real sense of living with a potential ghost out there."

She says a six-month anniversary is a very short time in a missing persons journey.

With "traditional loss" people start to get back some level of normalcy in their life by this stage, whereas with missing people it is a significant amount of time, she says.

"The families I've interviewed say that it can be five 10, or 15 years after the fact where they start to come out of the fog, because they have to learn to come to terms with the fact that they just might not find out what happened to somebody, and that's really complicated."

She says it's important at this stage to tread very gently with the families and allow them to acknowledge the space they are in, "without rushing in with ideas of where else you could be searching, or what miraculous missing persons case was resolved in another country."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 14 seconds 14 s A new video of missing Belgian teen Theo Hayez

"[It is about] just really sitting with the fact that this beautiful boy was here, and we don't know where he is at the moment, and we don't know when this nightmare will end."

Around the time news came in September that the police investigation into Theo Hayez would close and the case formally handed to the coroner, supporters held a candlelit vigil at Clarke's Beach in Byron Bay with the Hayez family.

Jean-Philippe Pector remembers a line that Ms O'Keeffe said in a speech at the event, that: "Everything will be all right in the end. If it is not all right, it is not the end."

"We don't want to give up hope of finding answers," he says.

"We will fight for Theo, for his little brother Lucas, in the name of love."