The 15-year-old's body was found in dense woodland in Malaysia earlier this week.
She had been missing for more than a week after vanishing from her family's accommodation whilst on holiday at the Dusun Resort.
In a statement on Friday morning, the school girl's family said: "The initial post-mortem results have given some information that help us to understand Nora's cause of death.
"But our beautiful innocent girl died in extremely complex circumstances and we are hoping that soon we will have more answers to our many questions.
"We are struggling to understand the events of the last 10 days."
The family thanked police and authorities who helped with the search effort, adding they are planning to lay her to rest "close to her loving families in France and Ireland".
A hotline remains open to gather information about the disappearance of the teenager.
Police had previously said Nora - who was born with the brain defect holoprosencephaly, which her family said meant she struggled with everyday tasks - was believed to have climbed out of her resort room window.