Police divers have joined the search for the knife used to stab father-of-two Aaron Hadfield in Wellington.
Mr Hadfield, 27, was stabbed to death on Thursday in an incident thought to have been sparked by road rage, just a few kilometres from his home.
It is believed he was returning home from picking up prescription medicine for one of his young children.
Bystanders tried to revive him after he staggered from his car and collapsed but he died after being taken to Hutt Hospital.
Two men, aged 20 and 22, later handed themselves into police and were both charged with assault, with further charges expected before their next court appearance.
Neighbours said Mr Hadfield's vehicle stopped before man reached into the car and was seen to punch him.
Detective Senior Sergeant Scott Cooper said today that police were still looking for the knife used in the attack.
Police specialist search group and dive squad members scoured an area of Delaney Park and Speldhurst Park today, but no significant items of interest were found.
Mr Cooper said a scene examination was completed over the weekend and a forensic examination of Mr Hadfield's vehicle was continuing.
Police were still trying to identify all the witnesses in the area before the altercation.
They were looking to talk to a man seen talking to the alleged offenders that afternoon.
"He may have been a door to door salesman and has been described as being in his 20s with curly hair, wearing a yellow name badge on his chest and carrying satchel,'' Mr Cooper said.
Police also wanted to speak to a group of three men in their 20s, possibly of Pacific Island descent, who were seen walking along Logie St about 9pm Thursday.
"These men may have witnessed an altercation involving two males and Mr Hadfield. We would really like those people to come forward and speak with us.''
Family yesterday gathered at Te Mangungu Marae in Naenae, where Mr Hadfield's tangi will be held.
The two men charged over the stabbing were both granted interim name suppression and remanded in custody when they appeared in Lower Hutt District Court on Friday.
The 22-year-old man will reappear on February 9 and the 20-year-old man is next in court on February 14.
