She has a condition called "holoprosencephaly", which means she has a smaller-than-normal brain, and has limited verbal communication and can not write more than a few words.
They believe it is likely she was abducted.
"It may have been they just got lucky", he said of the discovery yesterday.
France's Foreign Minister Jean-Yves Le Drian said on Tuesday night that the country's authorities were ready to investigate the circumstances of her death.
A team of almost 350 people was created to search for the girl.
Calls offering help poured into the Lucie Blackman Trust.
Four days after the teen went missing, officials hunting for her in the dense jungle played a heartbreaking recording of Nora's mum calling "Nora, Nora darling, mummy's here" through loudspeakers in an attempt to reach her.
On Monday, the mother, Meabh Quoirin, announced a 50,000 ringgit ($18,000) reward, donated by a Belfast-based business, for information leading to the recovery of her daughter.
The teenager's devastated family faced an agonising wait last night to find out whether her death had resulted from an accident or a crime.
But, for the Quoirins, there will be no end to the devastation or the grief that was visited upon their lives during a brief stay at a remote eco-resort that robbed them of their bright future with their precious daughter.
However, he said there were no reports of obvious damage to her body - from a struggle, injury or mauling by an animal.
Her relatives said the schoolgirl was "at the heart of our family", in a statement released by The Lucie Blackman Trust, a United Kingdom charity that supports relatives of British people missing overseas.
A body has been found during the search for a British teenager missing for more than a week in Malaysia.
Following the discovery, the schoolgirl's devastated parents, Meabh and Sebastien, were taken to the area where her body was found. However, she was nowhere to be found the following morning.
They were later supported at the resort by relatives who had flown in from Singapore, London and Glasgow.
The McCanns were at one point named by Portuguese police as suspects but later cleared.
Nora's parents had earlier thanked those involved in the search operation as fundraising pages set up by the teenager's aunt and uncle raised more than £100,000. According to the BBC, the investigation has cost more than $13 million so far.
Taoiseach Leo Varadkar tweeted: "Our thoughts & honest condolences are with Nora Quoirin's parents, siblings & wider family at this unimaginably hard time".
Nora's disappearance "brings back the horror of Maddie vanishing", the family said.