"The case is still open, they won't give up."
Nigel, then 33, went missing on November 17, 2017 after he was moved by caregivers from his much-loved flat due to the hot water cylinder bursting.
He was in full-time care as he suffered from psychosis and autistic symptoms following a childhood illness which affected his brain.
The last verified sighting of him was by a caregiver around 3pm on Old Taupo Rd after he jumped out of a car.
There were a few likely sightings over the next week, including one on the following Wednesday at the Tamaki Māori Village, but then nothing.
"You can never have no hope as a parent, but I can't get past [the idea] that he's been a victim of some misadventure," Peterson said.
"You can speculate, but then you just drive yourself mad."
The officer in charge of the case, Constable John Frederickson, told NZME in August he was certain Nigel was dead.
A second search was completed in May this year after a behavioural science profile was completed to give police a better idea of his likely movements.
Police had already done a door-to-door search of 1200 properties and even used a heat-seeking drone in the weeks following Nigel's disappearance.
Nigel's mum Eileen Goldsmith is heading to Rotorua too, as are Chris' youngest two daughters, and they will have a casual lunch with Nigel's flatmates.
"We're not making a big thing of it to be honest," Peterson said.
Any information on Nigel's disappearance can be given to Rotorua police on (07) 348 0099 or the anonymous Crimestoppers line on 0800 555 111.
