Police follow up tips in search for missing 19-year-old Maia Johnston

The mother of 19-year-old Maia Johnston missing from Upper Hutt since Saturday has pleaded for her daughter to come home.

Police set up a base at a local school as the search for Johnston continued.

The 19-year-old left a family address in Totara Park about 8.30pm on Saturday during heavy rain and has not been seen since.

Her mother, Amy Walsh, speaking at the search base on Monday made made an emotional plea for her daughter's return.

"Please just come home, she said.

"If you are alive and well I don't care where you are, I don't care what decision you made, I don't care who you are with," she said.

"I just want to hear you made a dumb decision and got in someone's car. Please just come home if you are still alive."

Up to 70 people were joining the search on Monday, managed by a volunteer coordinator from the base at Totara Park School.

Dozens of people turned up to speak with the coordinator and check a map of the local area before heading out.

The search is centered in the Totara Park area, which is surrounded by dense, bushy hills and Te Awa Kairangi, the Hutt River.

Police said they followed up a number of calls from the public after appeals for information but it didn't lead them to Johnston's whereabouts.

On Monday afternoon police said they were asking anyone in the areas of Totara Park, Harcourt Park and Brown Owl check their properties including any outbuildings such as sheds or sleepouts to see if Maia might have gone in there.

They were continuing to ask those who live in those three areas to check any CCTV footage for sightings.

Johnston was last seen wearing a black cardigan or light top, dark shorts, and black and white Converse shoes.

Johnston, her sister and brother, and some friends had travelled down from Hamilton, where they live, for an early family Christmas with Walsh.

It had been a happy day, Walsh said

Johnston and her best friend Kerry had been to the park in the early evening and sat chatting on the doorstep when they returned, Walsh said.

"Maia said to Kerry about 8 o'clock, I just need some time by myself."

That was not unusual, Walsh said, and Johnston had not been upset.

"There was nothing out of character to need a bit of fresh air. So she's walked off with just a vape," Walsh said.

But after about half an hour, Kerry realised Johnston had left her phone behind, and went looking for her friend in the pouring rain. Another half hour later, about 9pm, Walsh got in the car to try to find what she thought would be "two wet girls" at the park - but only Kerry was there.

They have been searching ever since - Walsh had not stopped since midnight Sunday.

"I had to force myself to go home and get some sleep so I could function today, and that was the worst feeling in the world, going home without my daughter," she said.

Walsh was worried her daughter had hurt herself, and that she had left her phone at home intentionally.

"There is a really small chance that she may have hopped in a car with somebody going to a party. Just be with other people she doesn't know.

"If it was just me, I would say 100 percent that sounds on character, that she wouldn't think that I would get worried, she wouldn't notify her parents, that's normal.

"For her best friend to be at my house, worried about her whereabouts, I just find it impossible to believe that she would willingly go to a party or go for a drive or hitchhike somewhere knowing her best friend would be worried about her."

Walsh said she was "absolutely blown away" that so many strangers - hundreds, she said - had turned out to search for her daughter.

The base at Totara Park school was set up to help create a more coordinated approach, she said.

Johnston's father was flying down to join this search on Monday afternoon, and her grandmother had looked through Johnston's house in Hamilton, and asked neighbours to call if she returned home.

While the search was focused in Upper Hutt, Johnston could be anywhere in New Zealand, Walsh said.

She described her daughter as an "amazing, beautiful person".

"She does struggle with mental health, but she is so, so determined to be more than her mental health and to not get her mental health get the better of her.

"It's not always an easy place inside her head, but she wants better."

Anyone with any information or CCTV footage can updated police online, or call 105, using the reference number 241222/0237.