Phil Cottrell was left unconscious with broken bones and a shattered skull in central Wellington last year.
The 43-year-old who suffered from a brittle bone disease, was found by a taxi driver on Boulcott Street early on December 10.
He died from his injuries in hospital the next day.
Nicho Waipuka, 20, and Manuel Robinson, 18, are on trial for his murder in the High Court at Wellington.
The Crown says they attacked Mr Cottrell on Boulcott St as he walked home from his overnight shift as a bulletins editor at Radio New Zealand.
A co-worker, Colette Jansen, today described to the jury seeing Mr Cottrell as she was arriving at work about 5.30am as he was leaving.
They greeted each other by the elevators.
"He was really cherry, really happy. He had a big smile on his face, he had a twinkle in his eye," she said.
Also in court today, details were given of closed circuit television footage showing Robinson moments before Mr Cottrell was attacked.
Detective Constable Anna-lise Ferguson, who studied camera footage, said CCTV cameras fixed to the Telecom building on Boulcott Street captured Mr Cottrell's image at 5.36.02am.
Twenty-eight seconds later, Robinson was seen on the same camera on the other side of the road and about eight seconds after that, Waipuka followed him.
An associate of the accused, Anthony Perry told the jury he had dropped the pair at the James Cook Hotel very early on the day of December 10 - about 1am - so they could visit a girl.
He arranged to pick them up later, but when he returned, there was no sign of the accused.
Mr Perry said he waited for about an hour and a half and texted them about 20 times, but they never turned up.
Mike Antunovic, who appears for Robinson, said his client had nothing to do with the attack on Mr Cottrell, and he was on the other side of the road at the time.
Mr Paino, who represents Waipuka, said while his client admits to punching Mr Cottrell once in the jaw, he had no murderous intent.
Nearly 70 witnesses will be called during the trial, which is set down for two weeks before Justice Forrest Miller and a jury of seven women and five men.
