Bill McCormack still cries every day. His son Shannon died more than five years ago, but time does not heal such a wound.
"To some people it's like six years, but to us it's like six minutes," Mr McCormack said.
CCTV: Is this the man who king-hit Shannon McCormack?
Almost six years since Shannon McCormack, 22, died after being bashed outside a CBD nightclub, and CCTV released exclusively to The Age has seen a break in the case.
"It's always the same, it's always there. There's the aching in the heart, the absence of someone you love.
"I still cry every day, I still visit him in the cemetery. I still can't believe it happened."
Shannon was 22 when he was punched and hit his head on a wall and footpath outside a city nightclub on May 27, 2007. He died in hospital a week later.
Homicide detectives have this week released CCTV footage that shows a man who resembles Shannon's attacker, a move that Mr McCormack hopes will solve the case.
"There's never really closure on it, because when you lose a child you lose your future," Mr McCormack said.
"You lose your grandchildren, and the wedding, and the births and christenings and the Christmases.
"So there's never any real closure. We just want (the attacker) to be held accountable for what he's done."
He urged the people who are clearly shown speaking to the man in the footage to come forward.
Mr McCormack and his wife Cheryl have campaigned for higher quality CCTV cameras, for people to go to hospital when they receive a head injury, and for early intervention in primary schools for those with learning difficulties.
But he said a shift in the attitudes of young men was the greatest change needed.
Shannon McCormack's father reflects on CCTV
Bill McCormack says a man that has been newly-noticed by police in CCTV, matches witness descriptions of the person who king-hit his son outside a CBD nightclub, ultimately killing him.
He was "horrified" at the death of Templestowe man David Cassai, who was punched in the head outside shops at Rye last December and died shortly afterwards in hospital.
CCTV footage of the incident was used to identify Dylan John Closter, 18, who has been charged with manslaughter.
"One of the issues that continues to happen is that young men have no respect for each other. They think they're entitled to respect; they don't realise that you have to earn it, and you earn it through good deeds, not by demanding it," Mr McCormack said.
"Because someone walks in front of you, or someone crossed your path, and you hit them, that's not about respect.
"It's still the same (as when Shannon died). A lot of people seem to have lost manners and courteousness and respect. If someone bumps into you, you usually say sorry or excuse me, you don't whack them in the head."
Mrs McCormack said at an emotional media conference on Friday that while the break in the case was welcome, it reminded her that Shannon’s killer was still out there.
"It brings everything back," she said.
"The fact someone out there is walking around, leading their own life, and our son’s gone."