Surveillance footage has shown two people walking along Boulcott St around the time Radio New Zealand journalist Phillip Cottrell was attacked.
However police said the pair were not believed to be his attackers, and called for them to contact police to help with inquiries.
Cottrell, 43, died in Wellington Hospital Sunday after the attack in Boulcott Street, in the central city, early on Saturday morning.
He had left his overnight shift as a bulletins editor at Radio New Zealand (RNZ) on The Terrace at 5.30am and a taxi driver found him unconscious in Boulcott Street at 5.41am.
Head of the investigation Detective Senior Sergeant Scott Miller told Radio New Zealand a post mortem on Mr Cottrell is expected to be completed later today, while police would extend the scope of CCTV footage they are reviewing.