If you ever find yourself driving through Cadell, a town of 548 people in South Australia's Riverland (about two and a quarter hours north-east of Adelaide), you are likely to pass Barnett's General Store.

To the left of the shop's entrance, a vibrant and eye-catching mural calls out to those driving past. A sea-blue, aqua and violet background draws the eye toward the piece's subject: a young man with tousled brown hair and bright, engaged eyes.

Looking at it, you might assume that this is some local hero. But the 21-year-old man smiling out at passers-by hasn't been seen for 14 years — and never in Cadell.

He is Mount Gambier man — Ryan Chambers, who went missing while on a gap year in India in 2005 and hasn't been seen since.

Fourteen years later, with the help of Ryan's parents, Di and Jock Chambers, Adelaide-based street artist Joel Van Moore (aka Vans the Omega) has produced the mural as a part of a project that connects artists with the families of long-term missing persons, to create public artworks.

Ryan went missing from an ashram in Rishikesh, a town in northern India in the foothills of the Himalayas. ( Supplied: Film Camp )

The Unmissables is an initiative of the not-for-profit Missing Persons Advocacy Network (MPAN), which was set up to raise awareness around missing persons and support those left behind.

To date, the project has commissioned almost 30 artworks — specifically geared towards reigniting public interest in the cases of long-term missing persons.

"We really wanted to humanise missing people, especially long-term missing Australians," says MPAN founder and CEO Loren O'Keeffe.

"It's really hard for the families to maintain the public engagement over a long period of time."

The Unmissables is now the subject of a documentary series of the same name, which follows three artists — Moore, singer-songwriter Jess Ribeiro and sculptor Pimpisa Tinpalit (both Melbourne-based) — as they meet the families of the missing subjects, delve into their subjects' stories and, eventually, unveil their artworks.

Moore says taking part in the project was an overwhelmingly positive experience. "It was just really beautiful connecting [with Ryan's family] on that level in a positive way and then thinking, what can we do as a possibility and how can we make this grow?"

More than a few physical attributes

More than 100 Australians go missing every day. While most of those people are found in a matter of days or weeks, a sizable portion (over 2,600 annually) stay missing long-term.

When Loren O'Keeffe's brother Daniel went missing in 2011, she launched a huge social media campaign to find him.

Sadly, Daniel's remains were discovered in 2016; but the success of the campaign prompted O'Keeffe to found MPAN in the meantime.

A key aspect of the organisation's work has been dismantling "that association that missing persons as a topic has always had with police and crime", O'Keeffe explains.

"Only only 1 to 2 per cent of cases of missing persons are actually pertaining to crime. The overwhelming majority are [related to] a mental health issue, and it's very important that society start to understand that, so that they're not just desensitised to these missing posters with a mugshot and … date of birth and where they were last seen."

Singer-songwriter Jess Ribeiro wrote and recorded a song inspired by Elaine Johnson, who went missing in 1980. ( Supplied: Film Camp )

In fact, O'Keeffe cites recent research that suggests the traditional "milk carton" approach to finding missing persons is generally ineffective.

"Our facial recognition ability combined with our very limited attention span and pretty poor memory makes it really unlikely that people are able to recognise missing people from posters," she says.

With the Unmissables, which began life as a book publication called Too Short Stories and grew from there, O'Keeffe hopes to engage the public's imagination and heart while also providing comfort for grieving families.

"It's just really distressing to see your loved one whittled down to a couple of physical attributes that no-one is really going to be able to engage with," she says.

"The public needs to connect with a story to care, and that's what The Unmissables has proven to be so good at doing."

Making unexpected connections

The Unmissables invites the family members and friends of long-term missing persons to register their interest in the project via their website. Artists interested in the project are then able to log in and, as O'Keeffe puts it, "if [the story] of a certain loved one did speak to them a bit more, they'd be able to volunteer their time and donate their talent to that particular project".

However, Joel Van Moore was contacted directly by the project, with the help of the production team behind The Unmissables documentary.

The prospect of producing a portrait without ever meeting the sitter might sound daunting but Moore felt instantly attracted to the project.

"When they called me up to ask me to do it, I was just like, 'this was meant to be'," he says. "'I'm meant to do this, I know it.' It was just that instant 'you've got the right person'."

Moore has been creating art under his pseudonym Vans the Omega for almost 30 years. ( Supplied: Film Camp )

This feeling of connection, Moore says, was spurred on by the fact that his life and Ryan's had some interesting overlaps. "That he went missing in India, the timing of that ... I was there in India at almost the same time. I left like a month prior to him disappearing."

Moore went to India on a "massive spiritual journey … going to these amazing spots and doing a lot of meditation and other practices to evolve my mental state".

A series of notebooks that Ryan kept revealed that he too was doing some very deep thinking while on his journey through the subcontinent. The notebooks also revealed to Moore that Ryan was "a very good artist, like, a really good artist".

The strength of Ryan's work, a combination of pen sketches and writing, inspired Moore to include some of it in the background of his portrait, which used one of the last photos taken of Ryan as a model. "I was like 'OK, this [Ryan's work] is showing energy and movement. This has some incredible wording with it'," he says.

"I just felt like that was the perfect fit to go into the background ... the last things that he wrote down of his experiences in India."

"[It was] super interesting, this cross-pollination of Ryan and my life."

The location of the mural, too, has an unlikely connection to Ryan's story. Gordon and Lin, the owners of Barnett's, offered the wall up after reading about the project.

Gordon, who appears in the documentary, lost two brothers to suicide, and says, "it's different but it's a similar sort of thing because I ain't got any answers for that, and other people [the families of missing people] haven't got any answers".

New ways to engage the public

To date, The Unmissables hasn't "solved" any missing persons cases. But O'Keefe says this is only part of the goal.

"It's more about the hope and the love and the support that this is giving to the families and friends that are left behind, because that's immeasurable," she explains.

But she doesn't discount the potential value these artworks have in helping a case move forward.

"Of course, these artistic portrayals are not forensically valuable, but what they do do is they reignite interest, they re-engage the public, they get the media talking about it again. And that's what can lead to a breakthrough."

Pimpisa Tinpalit working on her study of Attila Bogar, who went missing in 2014. ( Supplied: Film Camp )

In Moore's case, this reignition of interest was almost instant.

"A bunch of people that I know and have been friends with for years contacted me saying 'I was Ryan's mate' and 'I hung out with Ryan', 'My parents live in Mount Gambier'," he says.

"We're all separated by one degree, if that. So, it's quite amazing."

At the time of interview Moore said these stories of connection to Ryan were being fed back to him "10, 20 times per day".

"It's going to perpetually grow in its interest, because it only takes one person to share that story."

"[In] my networks from being an artist and travelling, people now are saying, 'How do I watch it [the documentary]? I've seen the little clip on Facebook that's been shared, how do I watch it?' Then they're gonna share it, and it's gonna be back in India with millions of people being able to do it. So, that's the idea, just lighting this fire."

The Unmissables series is available to watch on ABC iView.