It is 15 years since Shannon McCormack died after a cowardly one-punch attack in Melbourne, and his family is still without answers.
His parents Bill and Cheryl McCormack have made an emotional plea for their son's killer, or those who know him, to come forward.
"You would think you'd have a conscience," Mr McCormack said on Wednesday as Victoria Police announced a $1 million reward to track down the 22-year-old's killer.
"The people who were with him while it was happening would all be married with kids now.
"How would they feel if one of their kids was beaten up like that?"
Time has stood still for the McCormack family since Shannon's death in 2007. Every event has been a reminder of his loss.
"When you lose a parent, you lose your past; when you lose a child, you lose your future," Mr McCormack said.
"He didn't just kill our son, he killed a whole generation of our family."
Police have also re-released CCTV images of the man they believe assaulted Shannon in the early hours of May 27.
Shannon left the Queens Bridge Hotel at Southbank about 4am. About 100m from the venue his group was involved in an altercation and Shannon was punched when he stepped in to break up an argument between his friend and another man.
"He was hit so hard, he was unconscious on his feet," Mr McCormack said.
Police believe he also hit his head on the ground.
Shannon was given first aid treatment and taken home in a taxi.
His condition deteriorated overnight and he died in hospital a week later.
Officers have poured over thousands of hours of CCTV footage and interviewed many witnesses since, but with no luck identifying his attacker, said Detective Inspector Tony Combridge.
Shannon's attacker was part of a group and it appears others in the footage knew the group as well, he said.
"Everyone in that footage will have a job, they'll belong to sporting clubs, they'll have friends of their own who might recognise him who can assist us," Det Insp Combridge said.
"It shouldn't be about the money; it should be about doing the right thing. After 15 years of living with this, it's probably time to do the right thing."
The suspect is between 165 and 175cm tall and was at the time thin to medium build with light brown or blonde spiky hair.
He was wearing a light purple or blue T-shirt and light blue jeans. Police also want to identify the man's friends.
Anyone with information should call CrimeStoppers.