The younger brother of one-punch victim Thomas Kelly was targeted with hazing and death threats, leaving the teen broken months before he took his own life, his parents say.

Speaking with 60 Minutes on Sunday night, father Ralph Kelly said abuse directed at his family over Sydney’s lockout laws weighed on his son, Stuart, who suicided in 2016.

“It took its toll in the end … We paid the price very badly for it,” Mr Kelly said.

The teen’s parents also said he became a different person overnight after attending St Paul’s College at Sydney University.

“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,” mother Kathy Kelly said.

Mr Kelly’s family said he didn’t leave his bedroom for months after spending one night at the college and never told them the full story of what happened but believed he may have been targeted in hazing.

Stuart Kelly was 14 when his older brother died after being randomly punched while walking with his girlfriend in Kings Cross in July 2012.

Following his brother’s death, Stuart went on to campaign heavily against alcohol-fuelled violence and to support the work of the Thomas Kelly Foundation.

The campaign, coupled with the death of one-punch attack victim Daniel Christie in 2013, eventually led to the controversial lockout laws being introduced by the NSW government the following year.

Ms Kelly said their family’s support for lockout laws had made them a target of abuse, including death threats.

“There were death threats and things like that to our family. What does that do to an 18-year-old?” she said.

Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14.

– AAP