By ANGELA GREGORY

A Hamilton man was said to be suffering from paranoid delusions when he fatally stabbed a picnicker at Maraetai last year, and was due to see a mental health worker the next day.

According to psychiatrists, John Karaipa Johnson was severely deluded and thought the "White Power" was out to shoot him when he stabbed Faletoi Kei at Omana Regional Park in April.

Johnson has pleaded not guilty to murdering the 41-year-old Mangere father of three by reason of insanity.

He similarly denies wounding a Hamilton man with intent to cause grievous bodily harm and assaulting a neighbour.

Johnson, 31, appeared in the High Court at Auckland yesterday.

Psychiatrist Dr Rees Tapsell told the court that Johnson's mental health had been deteriorating in the 18 months up to the stabbing.

Dr Tapsell, who gave evidence for the Crown, assessed Johnson after his arrest.

He said Johnson's problems had coincided with his use of pure methamphetamine or P.

Johnson had heard voices, which had become increasingly insistent.

His family noticed he had become withdrawn and preoccupied.

Dr Tapsell said Johnson thought there was a plot to shoot him and carve a swastika in his back.

"He thought there was a White Power movement plotting to kill him."

Johnson was smoking P daily to stay awake and hardly sleeping.

In April he had punched a neighbour because voices were telling him the man was going to "get him".

Days later he thought another neighbour was reaching for a knife or gun, and stabbed the man in the abdomen.

The man required surgery at Waikato Hospital.

Dr Tapsell said Johnson saw a family member who was a mental health worker.

"He had agreed to an appointment with a mental health professional but it could not be made until Monday."

Dr Tapsell said Johnson did not believe he could stay with his relative over the weekend as he would be killed.

He took a knife to protect himself and thought he would be safer outdoors.

On the Sunday Johnson drove to the Omana park and thought members of the Kei extended family who were picnicking there were laughing at him.