A mentally ill man whose father warned police he was a danger on the roads has been admitted to a psychiatric facility after being arrested for two separate offences over the weekend.
Fairfax Media has decided not to identify the man, who has bipolar disorder.
He was first arrested on Friday night for drunken behaviour, and spent the night detoxing.
He turned up at his parents' house on Saturday morning "so unwell it was unbelievable", his mother said.
Concerned for the safety of others on the road, his mother called 111 when he took off in his van.
The man's father, a former police officer, wanted police to take his son's keys off him.
Police could do this if someone was incapable of driving due to their mental or physical state, he said.
Police might have been able to prevent the events of Saturday night - when his son was arrested again - if they acted earlier, the father said.
"Had they done something on Saturday morning we may have stopped him either being assaulted or being involved in a fight and as I say, all they really needed to do was take his keys off him," he said.
But a police spokesman said "a number of proactive steps" were taken by staff after being contacted by the man's mother on Saturday morning.
"We did locate the vehicle at a nearby address, and staff spoke to the occupants of that address," the spokesman said.
The occupants told police they had no concerns for the man at that time, and that he was in the care of someone he knew, he said.
"So at that point we were reasonably happy that (a) he was in a better state of mind and (b) that he wouldn't be driving for the rest of that day," the spokesman said.
The man's parents received a call from a "really concerned" woman on Saturday night, saying their son was at her house, and behaving erratically.
"He had nothing whatsoever to drink at all that day and ended up at a barbecue and was obviously being obnoxious, and there was a fight - whether he was assaulted or not we don't know," his father said.
His mother called 111 for the third time that day, and the man's mental state was again assessed when police became involved.
"Actions took place and he was picked up and taken to the police station where he was assessed by the CAT team."
The crisis assessment and treatment (CAT) team provides assessment and short-term treatment services for people experiencing a serious mental health crisis and for whom there are urgent safety issues.
The man's father said: "We got a call at 6.30 in the morning [on Sunday] from a doctor saying he had been transferred to the secure unit of the psychiatric hospital in Wellington . . . We've got no idea how long he will be there for."
The man's driving licence could be suspended after the outcome of his mental health assessment, the police spokesman said.