They believe she may have been abducted despite the post-mortem stating otherwise.
The state police chief said Nora died from “gastrointestinal bleeding” and she had suffered “extreme stress” and “hunger”.
"For the time being, there is no element of abduction or kidnapping," he said.
“There is no indication she was raped."
Her naked body was found on Tuesday beside a small stream about 2km from the Dusun resort, where she had been on holiday with her parents and two siblings.
It is believed she had been alive for about a week, dying just two or three days before she was found.
The 10-day search for her involved hundreds of people, including indigenous locals.
A volunteer who helped in the search said that Nora's remains were found in an area that was previously searched by rescue teams, adding further mystery to the case.
Her family previously said their "hearts are broken" and paid tribute to her as "the truest, most precious girl".