Police are investigating after a man was found with serious head injuries on Auckland's North Shore.
The man was found in a garage in Birkdale on Wednesday afternoon and taken to Auckland Hospital.
Staff there notified police, but initial enquiries suggested the injuries were accidental.
Now the police say they are treating the injuries as unexplained after further information from medical staff.
The man remains in hospital in a critical condition.
A scene examination is underway and a team of officers will be making enquiries in the Birkdale area over the coming days.
Police are encouraging anyone who may have noticed anything suspicious around Verrans Road on Wednesday to get in touch.