Police are appealing for an Otorohanga man wanted in connection to a "horrific" double knife attack on his parents to come forward.
Clare Bremner, 60, was fatally stabbed last night and Keith Bremner, 64, was critically injured and is under guard in intensive care in Waikato Hospital.
Police have spent the day looking for the couple's son, 34-year-old Ross Bremner.
Detective Senior Sergeant Mark Greene said Mr Bremner lived at the house in the King Country town where the attack happened, and they needed to talk to him.
The attack was "horrific", he said.
Police were alerted about 8.30pm on Tuesday by a neighbour who saw and heard part of it.
Mr Greene appealed for Mr Bremner to come forward.
"Ross, we need to talk to you. We want to resolve it as early as possible and we'd like you to call into [the] local police station and talk to them and tell them who you are," Mr Greene said.
However, police didn't know whether he was still in the area.
"He could be anywhere," Mr Greene said.
The police were also looking for sightings of a 2003 silver Holden Vectra, registration BGP561.
Otorohanga mayor Max Baxter said the couple were well known in the small community and the death would have a big impact.
"The early stages of any tragedy such as this, there's always a lot of speculation, but as the details unravel, then I think there's going to be a lot more shock, and initially a lot of unanswered questions."
He said Mrs Bremner taught preschoolers with learning difficulties and helped the community in many other ways too.
Waikato DHB spokesperson Lydia Aydon said Ross Bremner had been a client of its mental health and addiction services.
He was last in inpatient care in 2013 and had been living in the community for the past three years, she said.
Anyone with information about Mr Bremner should contact police.