Police will officially join private investigators and local volunteers in scouring the Tasmanian wilderness for a Belgian tourist, two-and-a-half years after she went missing and a day after her mobile phone was found.

Celine Cremer’s Samsung phone was found by SES search and rescue volunteer Tony Hage on Saturday in the area around Philosopher Falls near Cradle Mountain in Tasmania’s north-west where the 31-year-old was last seen on 17 June 2023.

Inspector Andrew Hanson said Tasmania police had supported Cremer’s friends and family to privately arrange a search of the area this weekend – which, he announced on Sunday, officers would now formally join.

“Police were not leading or coordinating this private search, but we had been supporting the effort by sharing information and advice about what to do should anything be discovered,” he said.

“Yesterday, a bit before midday, the private search party located a mobile phone, which has been confirmed as belonging to Celine and will now undergo further forensic examination.”

Hanson said the phone was found in an area that “had been extensively searched previously”.

Photo from the initial search in 2023, showing Cremer’s SUV parked in bushland. Photograph: Tasmania police/AFP/Getty Images

“Phone data, as well as the location it was found, supports our theory that Celine may have, using an app on her phone, elected to leave the Philosopher Falls track to take a more direct route back to her car as daylight faded,” the inspector said.

“We suspect she dropped her phone and continued without it, becoming disoriented in dense terrain.

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Police believe Cremer had driven to Philosopher Falls, parked her car and set off on “what was meant to be a short bushwalk”.

“Unfortunately, she did not return,” Hanson said.

Nine days after her last confirmed sighting, Cremer’s friends reported her disappearance and police found her white SUV in the Philosopher Falls car park the next day.

“In the days since Celine’s disappearance, the winter weather in the area included sub zero temperatures, snow and rainfall,” Hanson said.

“Expert medical advice at the time indicated those conditions were not survivable for the duration she is believed to have been exposed.”

Illustrating how perilous and changeable conditions can be in the far-flung extremity at Australia’s southern edge, an independent controller postponed the search for Cremer on Sunday morning due to rain, hail and potential snow after a bushwalkers weather alert was issued by the Bureau of Meteorology.

The initial police search lasted for two weeks before being called off when experts made the determination that Cremer could not have survived. Despite numerous and extensive searches in treacherous terrain and challenging weather conditions since, no sign of her was found until Saturday’s discovery.

Rob Parsons, a Tasmanian historian who helped organised and participate in the search, posted on social media that “local legend” Hage found the phone after “more than 20 trips into the field [many of them solo]”.

“Tony located Celine’s mobile phone less than 100 metres from her last known GPS point,” Parsons wrote.

“This proves the theory that Celine lost her phone shortly after recording her final location and provides clear direction on the path she was heading.”

The search will resume once weather permits.

“When the search recommences, we will work together with the independent searchers to specifically re-search the area where the phone was located and the likely route Celine may have taken after losing it,” Hanson said.