Jayden Penno-Tompsett, who went missing from Charters Towers on December 31, 2017, and who was considered by the state's coroner to have perished in the scorching heat only days later, was remembered fondly by his family and friends at a memorial service attended by around 100 mourners at Belmont on Saturday.

Jayden's family have never given up the search for their lost son and, at odds with the coroner's findings, believe there is more to Jayden's tragic fate than has yet been uncovered.

As memories of Jayden were recounted through tears at the weekend, his family pleaded for answers from anyone who could know more about the disappearance that sparked an exhaustive police search, a desperate search for answers, and plunged his loved ones into a years-long hell of grief and despair.

"I wish you could see what I can see because it would change the way you look at things," celebrant Carolyn Read, who conducted the memorial and read remembrances penned by Jayden's family and friends, said Saturday morning. "I can see the pain - the absolute searing pain.

"Someone, somewhere, knows something. You may know something that's so small that you think it's insignificant ... that you think doesn't matter. But ever piece of the puzzle is a piece of the puzzle.

"And not knowing is like a thousand tiny cuts. Knowing is much better - knowing lets you say goodbye rather than clinging to hope."

In May, Queensland coroner Nerida Wilson ruled that Jayden had likely perished when he walked off from travelling companion Lucas Tattersall at Charters Towers after a roadside argument during a holiday trip to Cairns.

He was exhausted, disorientated from days without sleep and, police believe, likely did not survive the three days before he was ultimately reported missing. His body has never been found.

Sceptical of the coroner's findings, however, and desperate for answers, Jayden's family have hired Sydney private investigator Ken Gamble who has spent the last six months re-examining the case - including evidence from the extensive search and police investigation, and now four-year hunt for answers by Jayden's grieving mother - in the hope it will lead to closure.

Mr Gamble, who attended Saturday's service, said he planned to travel to Charters Towers in the New Year, as COVID-19 restrictions eased, and had spent the previous months combing through "digital data" to reconstruct Jayden's final days, though admitted there was no clear evidence to suggest foul play in the disappearance.

"While a lot of people are concerned that there may have been foul play, there no clear evidence," he said. "There are possibilities that he may have gone a lot further than where the police searched ... (but) at the end of the day, we just want to make sure that (Jayden's mother) and the family have got the very best possible help, and that the investigation is done as thoroughly as possible.

"We're always hopeful that we can come up wth some more information that may just open up new lines of inquiry."

During the service, Ms Read spoke for Jayden's grandmother who remembered him as a doting grandson, loyal and caring for his family with a "daredevil" heart.

"When he was nine or 10 years old, he would visit my dying husband and keep him company," she said, "When Don died, he would still come to my place instead of playing with his mates, telling mum that grandma might be lonely on her own. These were the actions of a kind-hearted boy. Jay was no angel, but he had a caring nature."

"There are many people who miss Jay - I miss him - but no one more than his mum who has been devastated by the disappearance of her only child. She taught him to care about people."

Jayden's aunt, Karen, who asked that her surname be withheld, said that whatever "trouble you may have got yourself into", her nephew was loved and missed at every moment.

"You were and still are a cherished son, grandson, nephew, cousin and friend and that's my fear - that people will forget this," she said. "You meant the world to us and you are missed and loved dearly and we will continue to fight to find and bring you home."

"Your big, beautiful smile and laugh are gone, and I will never forget you. I wish I could hug and laugh with you one more time.

"You left this world and not a sound was heard. You were alone and none of us had the chance to say goodbye."

Jayden was 22-years-old.