A post-mortem has revealed 15-year-old Nora Quoirin is likely to have starved to death after spending a week in the Malaysian jungle on her own. 

Police said she had been dead for up to three days when her body was found. She is believed to have suffered intestinal bleeding due to lack of food and stress.

Negeri Sembilan state police chief Mohamad Mat Yusop said: “For the time being, there is no element of abduction or kidnapping. 

“The cause of death was upper gastrointestinal bleeding due to duodenal ulcer, complicated with perforation … it could be due to a lack of food for a long period of time and due to prolonged stress.”

He added that there were some bruises on her legs but that these would not have caused her death 

Further analysis is due to be carried out on samples taken from her body, he said, adding that Nora’s family are now free to take her back home.

The teenager, who was born with the brain defect holoprosencephaly and was described by her family as “vulnerable”, went missing on Sunday August 4.

Her body was discovered on Tuesday by volunteer helpers just over a mile from the Dunsun forest eco-resort in southern Negeri Sembilan state, where Nora, her parents and two younger siblings was staying, following a 10-day search. 

In a statement released on Wednesday, Nora’s family said their “hearts are broken” and paid tribute to her as “the truest, most precious girl”.

They said: “Nora is at the heart of our family. She is the truest, most precious girl and we love her infinitely. The cruelty of her being taken away is unbearable. Our hearts are broken.”

They offered thanks to those involved in the search for the teenager, adding: “Nora has brought people together, especially from France, Ireland, Britain and Malaysia, united in their love and support for her and her family.”

Deputy police chief Mazlan Mansor told reporters at a press conference on Tuesday that the body “was not in any clothings” and that the probe was considering all possibilities, including the “angle of criminal investigation”.

He added that the body was found in an area that had previously been searched by rescuers. 

Family spokesman Matthew Searle, of the Lucie Blackman Trust, told The Sun the Quoirins still have “a large amount of questions.” 

He said: “One of those questions is, has the body been there all the time or is there a criminal involvement? Was the body dumped there afterwards?”

The teenager’s Irish-French parents Meabh and Sebastien Quoirin, who have lived in south west London for 20 years, had said Nora was wearing her undergarments when they put her to bed, though it was unclear if she was dressed or undressed when she disappeared. 

A downstairs window, which reportedly can only be opened from the inside of their apartment, was found wide open on the morning the teenager went missing. The window of the bedroom Nora was sleeping in with her siblings was also open, it is reported. 

During the search, Quoirins, thanked those looking for her, as fundraising pages set up by Nora’s aunt and uncle collected more than £100,000 from well-wishers.

A book of condolence was opened on Wednesday at the city hall in Belfast, where Quoirin is from, with Lord Mayor of Belfast John Finucane the first to sign it.

He said the teenager’s death was “heart-breaking”, and praised the “clear and positive” show of solidarity from the Belfast public.

A special service was held on Tuesday at the south Belfast church where Nora was baptised. Her grandparents are parishioners.

The head teacher at Nora’s school in Wandsworth, south-west London, paid tribute to her as “a delight to work with” and said her fellow pupils and others who knew her will be supported during a difficult time.

The Quoirins said Nora’s condition meant she was not independent and had difficulty walking.

Describing her as a “very special person”, they said she would not have gone anywhere alone.

In a statement released last Friday, they said: “She is not like other teenagers. She is not independent and does not go anywhere alone… her verbal communication is limited. She is unable to do maths and so things like money are impossible to manage.” 

Search crews looking for the teenager played her mother’s voice in the dense Malaysian forest near where she disappeared. Mrs Quoirin could be heard saying “Nora, darling, Nora, I love you, Mum is here,” on the recording.

Police had said Nora, who was travelling on an Irish passport, was believed to have climbed out of her resort room window. A spokesman speaking to reporters at a hospital morgue, said no evidence of abduction or kidnapping had been uncovered “for the time being.” 

Two days after Nora went missing, her family said they did not think she would have wandered off alone and believed she had been abducted.

The Paris prosecutor had opened a criminal investigation into Quoirin’s case for kidnapping on August 9, a spokeswoman told Reuters news agency.

French prosecutors regularly launch investigations on cases involving French citizens abroad. Nora’s mother is from Belfast while her father is French. The family lived in Balham, London.

A police press conference is expected to take place later today.