The mental health service at Middlemore Hospital in South Auckland has been faulted over the death of a Dunedin man in 2014.
Mental Health Commissioner Kevin Allan lists a series of failings and says the Counties Manukau District Health Board breached the patient's code of rights.
The police had found the Dunedin man, in his 50s, wandering outside an airport, who was then taken to care.
Following the inquiry, Kevin Allan suggests the DHB consider having psychiatrists on duty during weekends and public holidays.
The DHB said it offered its sympathies to the man's family and had apologised.