Police eventually arrested him in an estuary not far from the home.
The murder came after Tait's parents had repeatedly sought help for their unemployed son's mental health issues.
Over a 16-year period, Mrs Tait approached the Western Bay of Plenty Mental Health Trust three times and on the fourth visit was referred to the ToughLove programme.
Yesterday, she said the trust had told her it could not help her son as he was in no danger to himself or his family - a response her GP described as "standard".
After meeting a ToughLove social worker and being encouraged to confront their son, the Taits began a new regime, including denying him his favourite grocery items.
But it only angered him.
What they didn't know - until it was revealed by a forensic psychiatrist after the murder - was that Tait suffered a deteriorating, severe obsessive compulsive disorder.
Mrs Tait said she and her husband were left terrified after two violent episodes, one in which their son threatened his father with a brick.
Mrs Tait said: "He should have been 'sectioned' then ... He was a danger to us. Nobody said, 'Perhaps you should see a psychiatrist'."
Under questioning during Tait's trial in June, ToughLove social worker Donald Welsh was told "alarm bells should have been ringing" because of the couple's previous contacts with agencies and Mr Welsh's case notes, which mentioned possible obsessive compulsive disorder, personality disorder or even post-traumatic disorder.
Mr Welsh responded that his notes were just his opinion.
Western Bay of Plenty Mental Health Trust manager Sally Duncan declined to comment.
Mrs Tait was unsure whether she would lay a formal complaint.
"They just needed to have all the facts ... They sympathised, but they didn't do anything," she said.
Despite their often-strained relationship, Mrs Tait said the two men loved each other. "Murray loved his father. I think it ... wouldn't have happened if he'd been sectioned."
Justice John Priestly acknowledged the family's attempts.
"Their dilemma, in my view, exemplifies the weakness of the mental health system where treatment is unavailable on any compulsory basis, unless it clearly points out a danger to self or others."
The judge said the ToughLove regime led to a marked decline in Tait's condition, and its eventual diagnosis was the "missing piece of the jigsaw" the family had been searching for. But he did not take away from Tait's brutality.
Tait was sentenced to life imprisonment for a minimum of 10 years and was urged to take up a treatment regime.