Members of the public witnessed the stabbing that killed a homeless man in central Auckland's Myers Park late last night, police say.
Steven Harris, 54, was stabbed in the upper body. Witnesses rushed to his aid and called emergency services, but Mr Harris died later in hospital.
Police believe Mr Harris was attacked under the Mayoral Drive overbridge, and will be doing luminol testing in that area to detect blood.
A specialist search group will be in the park tomorrow morning looking for the weapon used in the attack.
"Several items of interest have been recovered from the wider scene today and our objective tonight is to firm up on the attack scene and locate evidence that is not immediately obvious to the naked eye," said Acting Detective Inspector John Sutton.
Mr Sutton said police were still hoping to hear from three Asian people - two men and a woman - who were understood to be nearby when the incident happened.
"We'd like to identify and speak with them to determine whether they have any information that might assist us," said Mr Sutton.
Witnesses also told police a man was seen running up Myers Park, towards Karangahape Road.
"We know that for the past few weeks the deceased had been staying with an associate at an Epsom address but prior to that he had been a street and park dweller in and around the city," Mr Sutton said.
CCTV footage from around the area is being analysed in an effort to identify Mr Harris' attacker.
Police say there is no clear motive for the violent attack, which comes just weeks after another homeless man was killed in Mills Lane, also in Auckland's CBD
Mr Sutton says police are confident the last night's attack is unrelated to the one at the end of July. Edwin Linder, 42, was found unconscious in Mills Lane and later died in hospital of his injuries.
A 17-year-old man has pleaded not guilty to murdering Mr Linder.
Myers Park is still closed to the public while the scene examination is carried out.