Rotorua Police say they are still receiving information about sightings of Rotorua man Nigel Peterson, who went missing in Rotorua on November 17.

Nigel is autistic and went missing after he had to move out of his home temporarily.

Police have sought the expertise of the Behaviour Science Unit to build a better understanding of Nigel and to establish his movements around the time he went missing, says constable John Fredericksen.

Volunteers, friends and family are still searching areas across the wider Bay of Plenty and police appeal to the wider community to continue to contact Police if they believe they have information that can assist.

Police urge people who are reporting sightings to take the time to record as much detail as possible about the person they have seen and report it in a timely manner.

Please call 111 if you have just seen a person you believe to be Nigel or Rotorua Police on 07 3480099 if the information is historic.

Michelle Peterson says her brother Nigel was last seen on Otonga Road, heading towards Old Taupo Road, in Rotorua.

'He has a home in Rotorua with flatmates and caregivers, which he loves,” says Michelle when interviewed earlier.

'But the water cylinder flooded and they had to move to another site for a week. He got confused and upset about that, thinking he wouldn't be allowed back. So he ran away, and now he's lost.”

Someone initially spotted him running away, and managed to keep up with him. But they turned back to get help, and by the time they returned to bring him back, Nigel was gone.

'He's very vulnerable, because he doesn't like to talk to strangers. He can be unsure of people – he can't tell if someone is good or bad, so he tends to avoid people,” says Michelle.

'He has certain anxiety traits that people should notice, though, like wringing his hands or talking to himself. We're asking people to keep an eye out if someone looks out of place.”