Three years after Stuart Kelly took his own life, his parents are still searching for answers.

CONTENT WARNING: This post deals with suicide and may be triggering for some readers. Please contact Lifeline Australia on 13 11 14 if you’re struggling with symptoms of mental illness.

“He was sitting in the gutter, with his head in his hands. When he got into the back seat of the car, he started to sob uncontrollably.”

When Kathy and Ralph Kelly picked their son Stuart up mere hours after his first night at University of Sydney’s St Paul’s College in 2016, they immediately noticed something in him had changed.

The boy they picked up from the side of the road wasn’t the same excited teen they’d left at a “jovial” freshers dinner the night before. Nor was it the child whose first words at one and a half years old was, “What a beautiful day it is today, Mummy.”

It was as though a switch had been flicked inside him, one that couldn’t be reversed.

“He’d lost his way [after that night],” Ralph Kelly told Andrew Denton on Tuesday night’s episode of Interview. 

He refused to go back to university and barely left his room for two months.

A few months later, that very same year, Stuart Kelly took his own life. He was 18 years old.

He had the world at his fingertips, but it was one that had been turned upside down four years earlier by a family trauma no sibling could possibly imagine.

His older brother Thomas – also aged 18 – had been killed in a random, one-punch attack by an intoxicated stranger in Kings Cross. 

Stuart was 14, and like any younger sibling, looked up in awe at his older brother.

It was an incident that thrust the family into the headlines, not only because of the tragedy it was, but because of the cause they committed themselves to entirely after it happened – making Sydney a safer place for its inhabitants.

Ralph Kelly would work “18 hours a day, seven days a week” to achieve his goal, he told Andrew Denton.

He was completely and utterly immersed in his quest to ensure something like what happened to Thomas – a happy teen out with a girl he had a crush on – never tore another family apart again.

Two years later, he succeeded with the introduction of Sydney's lockout laws.

The laws required all nightclubs, bars and pubs in the CBD precinct to enforce a lockout at 1:30am (no new patrons to enter premises) and last drinks to be called at 3am. The legislation was highly controversial, with The Keep Sydney Open campaign leading to enormous demonstrations. Businesses argued that the laws were crippling them, and many said it was destroying Sydney's nightlife.

For the Kellys, it was a momentous step forward, but their journey wasn't over. Obstacles were ahead.

In 2015, Stuart himself fronted 700 people at a Take Kare Gala Dinner to raise money for the Thomas Kelly foundation, the body the Kellys established after Thomas' death which lead the campaign in changing Sydney's licencing laws.

Stuart, a 17-year-old days away from graduating at the time, maintained his composure as he called on the NSW Premier at the time, Mike Baird, to maintain the state government's position on the lockout laws to prevent any more senseless violence.

After describing the hole left in his life after Thomas' death, Stuart stood strong as he called for a firm stance in the face of the issue.

"It's time for change. Action is needed through strong leadership from the NSW state government and the federal government. Action is needed by our friends and our families across all of our communities - change to stop the growing epidemic of drug and alcohol abuse and misuse that is turning now into senseless violence,"he said.

"Australia is an alcoholic; we need to rethink the way we drink."

It was a speech that moved a room full of Sydney's most powerful people to tears.

But a year later, when the laws came under review again, those words became the fuel for a hate-filled campaign against the Kelly family.

"They called him a puppet, because of that speech. A private school puppet," Ralph recalled of the online bullying Stuart faced.

It was Stuart's perceived involvement in changing the lockout laws that led to him being tormented at St Paul's, his family believe. A night they believe tortured their son to the point of no return.

LISTEN: Mia Freedman speaks to Kathy Kelly about the grief of losing both sons on No Filter. Post continues below. 

"There is still a police investigation going on as we speak," Ralph said of the night in question.

"We have been advised that he was held down, with alcohol poured down his throat. He was made fun of because of the lockout laws," Ralph continued.

"He asked the people holding him down to stop, but they didn't. Eventually he broke free, and basically he wasn't seen again until when we picked him up outside RPA medical centre at four o'clock the next afternoon."

"So they say," his wife and grieving mother Kathy Kelly interjected.

She elaborated: "There's this mystery, somebody knows where he was and what happened to him that night... It just seems to me that he was somewhere against his will, and whatever that entailed... I feel there was a level of... I don't think embarrassment is the word, but something along those lines that he couldn't live with. Shame, maybe, that he could never divulge to us."

"We left what we thought was a pretty happy kid... [Afterwards] he refused to go back to uni, and wouldn't explain what had happened," Kathy recalled.

"I would go in and try to talk to him about things and he'd say, 'We are not discussing it. Leave me alone.'"

His mother wasn't the only one he kept the events of the night from.

Following Stuart's death, a girl he'd been speaking to online got in touch with his sister Maddie. She told her when she'd asked Stuart about the night, he responded: "If you ever ask me again about that night, I will cut off all contact with you."

Kathy - who said goodbye to her youngest son Stuart three years ago, and her eldest seven - said she can't help but feel as though she "failed" as a parent.

"I kick myself now... I said all the wrong things," Kathy told Andrew Denton, fighting back tears.

"What happened to Thomas was a horrendous part of our lives, but he was happy when he died. He was holding a girl's hand, he was going out for a night of fun.

"This beautiful boy that was the joy of our lives didn't want to live anymore, and didn't want to talk about it to us."

LISTEN: You can listen to the full episode of No Filter with Kathy Kelly here. 

If you or someone you know is struggling with mental illness, please seek professional help and contact Lifeline on 13 11 14, Beyond Blue on 1300 22 4636, MensLine Australia on 1300 78 99 78 or Suicide Call Back Service on 1300 659 467. If someone is in immediate danger, call 000 immediately.