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Searchers are today combing the Waimakariri River area outside Christchurch for missing schoolgirl Marie Davis.

Police said today that last weekend - when 15-year-old Marie disappeared - there were a number of disorder and noise disturbances reported in and around the area.

Today, as part of normal investigation procedures these were being followed up, a police spokesman said.

The search is being conducted by 28 land search and rescue volunteers and police - all trained in tracking and search procedures.

Detectives investigating Marie's disappearance say the "logical conclusion" is that something sinister has occurred.

As friends piece together her final movements eight days ago, investigation head Detective Sergeant Virginia Le Bas said the possibility the 15-year-old had been abducted was becoming more likely.

"As time goes on we are thinking that ... that it is a bit more sinister."

A police forensic team last night finished their search of the family home in north Christchurch that Marie shared with her mother Janet and 17-year-old sister Amy.

Her family was moved to a motel while the team worked, but Le Bas would not be drawn on what police were looking for.

"The tests are normal and the same we would do for any investigation. We are following normal procedure."

A family friend who saw Marie's mother last night said she was "holding on by a thread".

Family spokesman and Marie's cousin, Nick Donald, confirmed the family was starting to struggle.

"Today has been the hardest day. Janet is not coping well, and Amy hadn't shed a tear until yesterday."

Marie has no bank account and Donald said he was pretty sure she didn't have a passport. Police inquiries into her cellphone records are continuing.

"I can't say any more than that," Le Bas said. "It's not as easy as it looks on those CSI shows."

Donald said the family still refused to believe the Papanui High School student had run away.

"She loved her home, she loved her mum and sister. Janet was a very good mum as far as I am concerned and Marie would not have done this to her family."

Marie was last seen when she was dropped at home by a friend's mother at about 5.30pm eight days ago.

Her mother had been away for more than a week and she was being looked after by Amy.

Her elder sister had made plans that Saturday night and asked Marie to clean the house in preparation for their mother's return.

Neighbours saw lights on at 10.30pm but when Amy got home at 8am last Sunday, the house was clean but Marie had gone.

Police can't confirm suggestions that all Marie's shoes were still at home but have confirmed an army-green shoulder bag is missing.

Police have investigated between 50 and 60 sightings but none has been confirmed.

Le Bas played down suggestions the keen photographer's alias on social networking site Bebo could hold the key to her whereabouts.

Marie called herself "Towards Darkness" which is also the title of a 2007 film about a young photographer who is abducted and held for ransom.

Friends and family stepped up their search yesterday, handing out missing person flyers in central Christchurch's cathedral square.

Among them was best friend Robyn Botha, who said Marie was like a second sister who told her everything.

"I don't think she would have gone anywhere willingly.

"She did not mention anything to me about being unhappy about anything."

Robyn's mother, Tracy, said Marie was part of the family.

"Over the last five years, Marie has spent about 65 per cent of the time at our house.

"She really is like a third daughter to me."

Robyn said the pair went horse riding together until they started having boyfriends a year ago.

"She wanted to be a forensic scientist when she left school. She's really interested in forensics."

Robyn said Marie hated having her photo taken but agreed to pose on Tuesday before she disappeared.

"I'm really glad that happened and I have those photos now."

- with nzpa