The man who killed 18-year-old water polo player Cole Miller in Brisbane’s Fortitude Valley in a random one-punch attack has been sentenced to seven years in prison.

Armstrong Renata, 23, pleaded guilty to unlawful striking causing death in the Supreme Court in Brisbane.

Renata punched Mr Miller in the back of the head while on a night out in the party precinct in January 2016, causing the teenager to fall and hit his head on the pavement.

Mr Miller, a former Brisbane State High School student, was walking through a mall with a friend to catch a taxi home when he was set upon.

The promising water polo player suffered severe head injuries and massive brain trauma and his life support was turned off the following day.

Thousands of people attended vigils and a rally in King George Square to show support for the Miller family shortly after and called for an end to violent behaviour.

Renata’s co-accused Daniel Maxwell, who started the fight after the pair had been kicked out of a venue,was given an 18-month sentence in August for assault.

He was deported back to New Zealand.

The families of both Mr Miller and Renata were in court for the sentencing.

Renata is the second person to be sentenced under Queensland’s one-punch laws.

‘Miller would not have seen the attack coming’

Prosecutor David Meredith said Mr Miller and his friend Nick Pace had no contact with Renata and Maxwell until the fatal event.

The court heard Maxwell was drunk and had picked three fights with people, before the two groups crossed paths in the Chinatown mall.

Maxwell challenged Mr Miller to a fight and punched him, aiming for his jaw, but the blow landed on his chest.

Mr Miller did not respond and indicted he did not want to fight.

Maxwell turned to Mr Pace and punched him in the chest. Mr Pace and Mr Miller backed away retreating.

Renata then attacked Mr Miller when he was facing away from him and had his hands at his side.

“Renata moved around behind Cole Miller and then punched him in the side of the head,” Mr Meredith said.

“Miller would not have seen the attack coming.

“The blow was of such force … it, as well as contact with ground … [meant] injury was unsurvivable.

“Miller had done nothing to Renata.”

—ABC