A man is under arrest in connection with the killing of a businessman at the BNZ tower in central Auckland.
The victim was trying to help a female colleague who had been assaulted when he was stabbed to death in Mills Lane at about 5:30pm on Thursday.
The Armed Offenders Squad raided a house in Otahuhu at 4:30am on Friday and arrested a sickness beneficiary, 45. He is to be charged with assault.
Police say they are not looking for anyone else in connection with the killing and further serious charges will follow.
Detective Senior Sergeant Gerry Whitley told Morning Report that help from members of the public led to the swift arrest.
He said the arrested man knows the woman involved, but would not comment on whether the accused was known to the police, or has gang connections.