Cops renew search, probe criminal link to missing girl

About 160 police and state emergency service personnel have been deployed to search 50 sq km of bushland near Nabowla, about 50km northeast of Launceston.

The operation, the largest of its kind in Tasmania's north, is expected to continue into Friday.

"Tasmania stands with Shyanne-Lee Tatnell's family and friends in their quest for answers," Tasmania Police northern district commander Kate Chambers told reporters. 

"We will not rest until we have those answers."

Detective acting inspector Andrew Hanson said a specific line of inquiry was being followed.

"All the inquiries we have done to date … all leads us down certain pathways. This is one of those," he said.

"From the start there is always the possibility that there is a criminal element to this investigation. 

"That is one of the avenues we're exploring."

Insp Hanson said police were acting on the basis of their inquiries and information from the public.

A specialist cadaver dog is also searching the North Esk River, near where Shyanne-Lee went missing and where initial efforts were focused.

Shyanne-Lee was last seen wearing bike shorts and a cream hoodie with dark writing across the chest and shoulder.

She is described as about 160cm tall with a slim build and blonde hair.

She had been staying in youth accommodation for the two weeks before her disappearance and was on her way to visit a friend in nearby Ravenswood.

Insp Hanson said all cars of interest in the Henry Street area at the time Shyanne-Lee went missing had been identified and drivers spoken to.

He said it was understandably a very harrowing set of circumstances for her family.

"As with any missing person case, everybody is hopeful they're found alive and well," Insp Hanson said. 

"With the passage of time, we're being pragmatic about it. 

"We understand the chances of Shyanne-Lee being found alive reduce with every day." 

Anyone with information has been urged to contact police.