He did not turn to face the gallery throughout his appearance, and kept his eyes to the front of the court.
Michael Douthett had earlier pleaded not guilty to the murder charge and there was discussion about whether he was fit to stand trial, and whether defence of insanity was available to him.
He had been remanded into a mental health facility, the Henry Bennett Centre.
Rosie Wallis, Patricia Douthett's sister, told the Rotorua Daily Post the family was relieved by the guilty plea.