"He might be trying to head there and might have got it completely wrong," Michelle said.
"He's vulnerable. He doesn't know how to communicate with strangers.
"He's very unsure about people. He might not approach people but he will be very noticeable, he will be very distressed."
Michelle and Nigel's other family members hoped people in Tauranga and the wider Bay of Plenty would keep a close eye out for him.
"He has not used his Eftpos card since Friday so he might be somewhere we haven't looked."
Nigel would be easy to spot as his distress would be obvious, she said.
"He will look like someone whose life has come crashing down and they don't know how to deal with it."
Michelle described her brother as slim and of medium height. On the day he went missing, he was believed to have been wearing a green T-shirt, light brown pants, brown sneakers, and possibly a denim jacket.
Nigel would likely be wringing his hands and could be talking to himself. Michelle said Nigel walks with quite an unusual gait and leans to the side a bit as he moves.
Constable Colin Fraser told the Rotorua Daily Post this morning Land Search and Rescue squads from Rotorua and Tauranga were today concentrating on the Otonga Rd and Old Taupo Rd areas.
Fraser said the teams would ask people to look around their properties for the missing man.
He said until now the search teams had focused on open spaces, including parks, reserves, schools, retirement homes and hospitals.
Nigel could be at someone's property without their knowledge, Fraser said.
"He could have easily wandered into the backyards and be in a garage. He could be sitting on a chair at the back of a garage waiting to be found because he wouldn't necessarily be able to seek his own help."
Rotorua police asked anyone who may have seen Nigel to contact them on (07) 349 9139.
