His family didn't know if he was dead or alive or if they'd ever lay eyes on him again.
But that didn't stop them from searching high and low in hope they would one day reunite.
Last week, their dedication to tracking down Jason, now 36, finally paid off when he was located living rough in the West Midlands, United Kingdom.
The family is now making preparations to bring him home to Brisbane after nearly two decades apart.
Jason's cousin Lisa Andrews told news.com.au she was still in shock that her relative, who she had grown up "very close to", had been found alive on the other side of the world.
"No one knew where he was," Ms Andrews said. "No one knew anything ... it was hell for all of the family."
He was living with an uncle, who was like a second father to him, when tragedy struck.
"They were out playing soccer and my dad (Jason's uncle) died of a massive heart attack on the field, he was 38," Ms Andrews said.
"Jason, who was only 19 at the time, witnessed it and saw them trying to revive him.
"He went to the hospital with them and saw the doctors running in and out of the room trying to keep him alive."
Ms Andrews said Jason stayed with friends before he was kicked out and became homeless.
"We lost contact with him straight away because he didn't have a number," she said. "That's all it took."
Jason's sister Sally, his mother, and extended family including Ms Andrews have spent the last 16 years trying to track him down.
"We went through all of the police channels but we couldn't file a missing person's report in the UK because we didn't live there and the Australian police couldn't do much either; we contacted the Department of Foreign Affairs and Trade; the Federal Police; Aboriginal Services; we put up a Facebook page hunting for him and we also printed lots of flyers and put them up in homeless shelters in the UK, everywhere," Ms Andrews said.
"No one can imagine what a family goes through in these sort of circumstances.
"Every birthday, Christmas, it was just devastation and sadness, wanting him to come home. Every (scenario) went through our heads ... we didn't know what had happened."
The family didn't find a single lead until last week when a call to UK police changed everything.
"They said (Jason) had been arrested (for petty crimes to get food) in the West Midlands in October 2014 and to contact the police there," Ms Andrews said.
"I contacted the West Midlands police and they said, 'Yes we have had more contact with Jason,' then they got in touch with him and passed on our message that we had been looking for him."
The police sought permission from Jason to pass his phone number onto his family.
"He said, 'Yes,' and the next day police called us and gave us Jason's number," Ms Andrews said.
"His sister Sally rang me and said, 'We've found him and he's alright.'"
Jason's mother was the first family member to call Jason.
"He was angry at first because he thought we had abandoned him," Ms Andrews said.
"He said he thought everyone had given up on him and that no one cared."
Jason revealed he had been living rough on the streets after falling on hard times. He was physically fragile.
"He's not OK," Ms Andrews said. "He's got a lot of health issues like arthritis from sleeping on the streets."
Ms Andrews spoke to her cousin over the phone just a few days ago.
"He said, 'I was hoping you would come and find me,' and, 'I'm not going to hold a grudge, you found me. I want to come home. I'm ready for this to be over,'" Ms Andrews said.
Jason is now staying at a friend's place while awaiting documentation to travel home to Australia.
His family created a gofundme page to raise funds to bring him back to Brisbane. The $2500 target was met within three days.
"He doesn't have a passport or ID as it was all stolen on the streets so we're just waiting for him to get all of that documentation so he can fly," Ms Andrews said.
"We're hoping he'll be back before his next birthday ... he's already missed 16 of them. We're ready to get him home."
Ms Andrews said it would take time for Jason to find his feet again but that their family would support him in the process.
"We don't know what he's been through, we're not sure of exactly what went on in that time," she said. "It's one thing to spend a little while on the streets but to be there a long time thinking no one wants you, I just can't imagine it.
"We're going to put everything in place so if he needs help he can get it. We don't want to rush him."
Jason has already revealed his first plan upon his return home.
"He wants to lay on the road in the middle of a big thunderstorm and smell the rain hitting the hot concrete," Ms Andrews said. "He said it's one of the things he misses most."
Ms Andrews said her family appreciated the assistance of British police and the public in helping to locate her cousin and bring him home.