A full review is to be launched into how a "frail" man was able to leave the rehabilitation unit at a Dunedin hospital and go missing this week, the district health board says.
Gordon McLean, 63, has been missing since Thursday when he left Waikari Hospital, and despite a search team of about 60 people combing the city and waterways, no sign of the man is yet to be seen.
Southern DHB's medical director for mental health, addictions and intellectual disability Dr Brad Strong said they were "increasingly concerned" for McLean's wellbeing.
He said McLean left the rehabilitation unit in which he was receiving care, and has not returned.
"Our focus at this stage is on working with the police and we thank all those in the community for any assistance they can provide to the search.
"Mr McLean was resident in a non-secure facility, however we will be fully reviewing the circumstances around his departure and care in light of these events."
About 60 LandSAR volunteers, Red Cross volunteers, a rescue search dog and police were set to continue searching Wakari, Helensburgh, Halfway Bush, Kaikorai Valley and Frasers Gully today.
Sergeant Richard Panting said police have asked residents to check their properties thoroughly, particularly in the Halfway Bush area. There was concern he may have fallen.
"Please check sheds and outbuildings in or around your properties," he said.
McLean was considered very frail and police have serious concerns for his welfare.
He was last seen wearing a dark-coloured polar fleece and trousers, a red polo shirt, brown slippers and a black puffer sleeveless jacket.
The 63 year old is approximately 152cm tall and of very thin build.
Police are following up all potential sightings of McLean which have come in from the public.
Any sightings should be reported to police immediately on 111.