The parents of Nora Quoirin, the London teenager found dead in a Malaysian jungle, have said they believe there was a criminal element involved in her death, and called for Malaysian authorities to open an inquest.

Speaking publicly for the first time since the death of 15-year-old Nora, Meabh and Sebastien Quoirin said many questions remain unanswered. “We believe it is a basic human right and democratic duty to seek truth and justice for Nora,” her father said in an interview with the Irish broadcaster RTÉ

Quoirin’s body was found unclothed and beside a stream, over a mile from the resort where she had been on holiday with her family. She was discovered in August by a group of hikers after a 10-day search of a Malaysian jungle that involved hundreds of volunteers, as well as officers from the UK, France and Ireland and local tribespeople.

Nora, who had special needs, had been sharing a room with her brother and sister the night she went missing. When the family awoke the following morning, Nora had disappeared and a large window in the hotel room was open.

The area where she was found was described as inaccessible, and her body had to be recovered by a helicopter.

Sebastien Quoirin said there was “one chance in a billion” that Nora had wandered off by herself.

Nora Quoirin. Photograph: AP

The family believe crucial time and evidence were lost because a criminal angle was not investigated quickly enough. Despite their repeated claims that she had been abducted, the police continued to treat the incident as a missing person case.

“For us something very complex happened. We have insisted from the beginning that we believe there was a criminal element to what happened,” her mother said.

Nora was born with the neurological disorder holoprosencephaly, which affects brain development, and her family described her as vulnerable. The Quoirins believe the Malaysian authorities did not understand Nora’s condition.

Nora’s mother said during Tuesday’s interview that it would have been “impossible physically, mentally to imagine that she could have got any distance at all”.

A recording of Meabh Quoirin calling her daughter’s name was played out across the jungle during the search for her. “Because of her needs, we were aware that a stranger calling her in the jungle – she wouldn’t respond to that,” she said.

“I called her by all the names that we had at home – ‘Nora Bean’. Nora was very tiny when she was born and I always thought she looked like she’d come out in the shape of a bean, and she loved that story. She liked being called Nora Bean at home. So I just call her by her name and hope that she could hear me and hope that she knew Dad and I were thinking of her every minute.”

An autopsy concluded that Nora was likely to have died of starvation and stress after spending seven days in the jungle.

“While a postmortem when it comes through may give us answers, and has already given us some basic answers around what caused Nora’s death, it doesn’t explain any of how she could possibly have got to where she was found,” her mother said.

“We really believe that that is going to be difficult to get the whole truth on, but it is important to try,” she added.

Mohammed Mat Isa, police chief for Negeri Sembilan state, said that it was too early to draw conclusions about Nora’s death and that toxicology reports were expected in the new year. A final postmortem would then be provided to the attorney general’s chambers, which would decide upon further proceedings, he added.