The parents of Stuart Kelly are calling for a coronial inquest into the teenager's death, saying he was exposed to "criminal" hazing rituals at Sydney University.
Kathy and Ralph Kelly said their son Stuart, who took his own life in 2016, became a different person overnight after attending a college at the university.
Stuart's death came less than five years after his older brother Thomas died when he was randomly punched while walking with his girlfriend in Kings Cross in July 2012.
At Stuart's funeral the Kellys were told their son had been held down by a number of boys and had alcohol poured down his throat at the college before he was able to break free, his father Ralph Kelly said.
"The rest of the night we have no idea what happened to him or the following day," Mr Kelly told 2GB radio on Monday.
"We don't know the full story ... we know he didn't sleep in his room that night."
A 200-page report, released on Monday, on sexual violence and hazing at university colleges has detailed a series of disturbing alleged rituals at Australia's leading institutions.
The damning report detailed long-running sexual humiliation rituals at Sydney University's residential colleges.
"It has been going on for a very long time and I think we were oblivious or naive to what happens during orientation week," Mr Kelly said in the aftermath of the report.
"It's well known by all the university that the culture is ingrained and can take many, many years to transition, but it's definitely not acceptable, in many ways its criminal activity."
Police have been investigating Stuart's death, but Mr Kelly is calling for a coronial inquest so they can find out what happened to his son that night at college.
"We know there would have been young men who either saw or later heard what happened to Stuart," he said.
"I lay there at night wondering how they sleep at night with this knowledge and we hope that more of them may come forward."
Mr Kelly hopes the inquest will lead to recommendations for colleges that will help keep students safer.
Last year Kathy Kelly told the Nine Network's 60 Minutes that Stuart changed overnight from his first night at the elite college.
"He went off to university at Sydney, for one night at a college, and he came home a different person the following day ... He was broken," Kathy said.
She said Stuart had called them the following day asking them to pick him up and take him home.
They found him sitting in the gutter with his head in hands at the nearby Prince Alfred Hospital.
"He didn't cry at (Thomas's) funeral. It was the first time I'd seen him cry since," Mr Kelly told Nine.
Following his big brother's death, Stuart went on to campaign heavily against alcohol-fuelled violence and to support the work of the Thomas Kelly Foundation.
The Kelly family's support for lockout laws had made them a target of abuse, including death threats.
