When a drunken thug launched at her boyfriend inside Crown casino, Tessa Penberthy tried to intervene.
Tyson Armstrong hit Luke Francis in the head twice, once with a closed fist and again with an open hand.
He took everything from the 29-year-old Melbourne concreter and his family, in the space of just 13 seconds.
"We were just going home, Luke didn't want any part of it," Ms Penberthy said outside the Supreme Court after Armstrong was jailed for up to a decade on Friday.
"He's got kids, he took that away from Luke - he didn't get a chance to have a family or a future."
Armstrong, a father of three, was intoxicated and looking for a fight when he encountered Mr Francis on the casino floor in the early hours of March 27 last year.
The pair exchanged words and Mr Francis started walking away, when Armstrong grabbed him from behind.
Holding his neck and chest, Armstrong pushed Mr Francis into some railing near the food court and punched him in the head.
He struck him again with an open hand and grabbed him by the throat.
Ms Penberthy pushed Armstrong away as Mr Francis collapsed behind her on the ground.
Armstrong taunted his victim, as he laid lifeless on the floor, saying: "You can't handle me, am I too big for you?"
He and his cousin then left, laughing, smiling and joking along the way.
Mr Francis' girlfriend and casino staff tried to revive him until paramedics arrived and took him to hospital.
But he had bleeding on his brain and could not be saved.
Mr Francis died in hospital a few days later, on March 29, after his family turned off life support.
Armstrong lied to police after being arrested and questioned about the beating.
He told officers Mr Francis was trying to get him to go outside for a brawl, so he punched him in the face.
Justice Andrew Tinney said Armstrong's lies were disrespectful, as he handed the "violent, drunken thug" a maximum 10-year prison sentence.
"This attack was not expected or anticipated by Luke and was a cowardly sneak-attack," he told Armstrong.
"By your mindless act of violence, you took the life of a much-loved young man with his whole life before him."
Mr Francis' mother said she was sickened by how her son was killed, calling Armstrong "nothing but a coward".
"I suppose the main thing is he's in jail but it's not enough," Michelle Harris said outside court.
"He's destroyed us all, absolutely obliterated us, we're gutted and it's something none of us will ever recover from."
Alcohol-fuelled violence was not new for Armstrong. He had prior convictions for assault in public after drinking.
Ms Penberthy said she hoped his sentence would send a message that "violence and alcohol is a problem and something needs to be done".
"No family needs to go through it," she said between tears.
Armstrong has already served six months in prison and will be eligible for parole after eight years.
