The parents of a missing Australian tennis coach believe their son is still alive and have made a desperate plea for help from the public to find him.
Sam and Richelle Arber travelled from Melbourne to join the search for 38-year-old Paul Arber, who they said was acting uncharacteristically the night before he left Australia to bring a group of teenage tennis players to Hamilton for a tournament.
"We feel he's still alive somewhere," Mr Arber said. "We have a gut feeling he is but we don't know where he is and we'd like the public to try and help us."
Mrs Arber's message to her son was to come forward if he can.
"We love him so much. We just want to hug him and hold him, and help him in any way he can. He may not feel that he needs any help. He may be very happy where he is right now but we just want to know that he's safe and well."
Paul Arber was last seen by a couple who coaxed him out of the Waikato River about 4am on Sunday after he failed to return from dinner to his group in Hamilton East on Saturday night.
Mr Arber called his son "almost perfect" and said he'd never been in trouble with the law and was a happy-go-lucky person who was well-known and respected in the Australian tennis community.
However he said the night before his son left for New Zealand he went to their house and spoke of a "love" and "warmth" he had for people and wanted his parents to share his feelings.
Only two weeks before that he had become a vegan and recently the "deep-thinker" had been reading more spiritual books which may have influenced him.
"He seemed very insightful, and talking about love. He wanted us to love ourselves. He said he had never felt better in his life, he suddenly felt this warmth. He wanted us to experience the warmth."
Mr Arber said the conversation disturbed him but he decided to address it when his son returned from the tournament.
"Hopefully we can find him."
Police said witnesses reported similar comments from Paul who was seen on Grey St in Hamilton East heading toward Steele Park about 9pm on Saturday.
It's believed he gave money to a homeless person, and patted a dog before talking to someone who had been attending a function near Galloway St.
After that he wasn't spotted until he was encouraged out of the river on Grantham St by two people walking over the Bridge St bridge at 4am the next morning.
Mrs Arber said Paul was an extremely positive person and the couple were trying to remain positive that he would be found alive.
She described Paul as a "terrific kid", a humanitarian and great athlete and coach who had never had mental health issues.
"There's not a bad word to say about him. It's just very worrying. Anyone who has been in this situation any other parent would know the fluctuations you feel in your mood, highs and lows but we're trying to remain positive as much as we can."
She urged anyone who had seen Paul between 10pm and 4am that night to come forward or if people found any of his clothing including distinctive orange and blue tennis shoes, and a grey tracksuit with a Wilson logo, "you can keep them, just let us know that you've seen them".
The couple spoke highly of police, media and the public in Hamilton and Auckland who had joined or reported the search for Paul.
They said the community had been very supportive.
"Everybody was so concerned and caring and we're very touched by everyone we have met in Hamilton and from the bottom of our hearts we thank you."
Waikato Field Crime Manager, Detective Inspector Karl Thornton, said land and water based searches would continue along with searches of buildings, parks and reserves.
He urged riverside residents to check their properties and river paths for any of Paul's clothing and asked people to keep an open mind about what had happened.
"It's important that none of us, police, searchers or the public become too focused on one point of reference and keep an open mind to all possibilities.
"At this point all the parties involved are working towards the goal of locating a vulnerable person who may need our, or your help and will continue to be so until such time as we have information to confirm otherwise."
Paul Arber is described as Caucasian; of slight build about 179cm tall with short dark hair.
He is a vegan who drinks only bottled water. Police, friends and family members assisting with the search believe Paul could appear vulnerable and disoriented.
Any information that may assist in locating Mr Arber can be provided to investigators by contacting the Hamilton Police Station on 07 858 6200 or leaving details at the mobile Police station situated at the southern end of Victoria St in Hamilton's CBD.
Alternatively, information can be left anonymously with the independent Crimestoppers on 0800 555111.