Nora Quoirin's family say they are hoping to get "more answers to our many questions" and that she died in "extremely complex circumstances".
It comes as the teenager's grandfather said there were "many dark areas that need to be cleared up" over her death in Malaysia.
The 15-year-old's body was found naked near a jungle stream on Tuesday, 10 days after she went missing on a family holiday.
An post-mortem examination found she died from internal bleeding, thought to be caused by prolonged hunger and stress.
A family statement on Friday 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 still struggling to understand the events of the last 10 days."
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The family also thanked Malaysian authorities and said they would be "bringing Nora home" to be "close to her loving families in France and Ireland".
Nora's grandfather, Sylvain Quoirin, has said is no way Nora would have ventured out alone in the middle of the night.
He told The Irish Times: "Can you imagine her walking 2.5km, naked and barefoot, over rocks, in the middle of the night? For me, that's absurd."
Mr Quoirin said Nora – who had learning difficulties – was extremely sensitive and shy and "clung to her parents and sister".
"If she went out alone by mistake, she would have banged on the door and screamed to be let back in," he said.
Nora's family initially feared she had been abducted, but so far police say they have found no signs of an attack or sexual assault.
Her body was found near a stream not far from the jungle resort where the family were staying – despite a major search operation going on for a week-and-a-half.
Nora's grandfather told the newspaper search members would not have missed her body: "She wasn't there yet. Someone put her there, to get rid of her."
An adviser to Nora's family, former police officer Jim Gamble, told Sky News there were still many questions.
He said: "We need to understand why over a period of six or seven days while she was alive – with an intense, well-resourced search going on in the area – she wasn't seen or located."
Mr Gamble said the window through which Nora is thought to have left the villa was broken and therefore "could be opened from the outside".
He said the family cannot understand how she would have got out the window by herself because there was a "significant depth" from the window to the ground.