Nora Quoirin's heartbroken parents believe there was "criminal element" in her disappearance and death.
Meabh and Sebastian Quoirin remain determined to get truth and justice for their 15-year-old daughter who went missing in the Dusun rainforest resort in Malaysia in August.
Her body was discovered nine days later in a ravine beside a stream.
Speaking publicly for the first time since the tragedy, Meabh said: "For us something very complex happened. We have insisted from the beginning that we believe there was a criminal element to what happened.
"And crucially we're struggling because it was difficult to get resources in place fast enough to investigate a criminal angle."
The mum, who lives in London, said it would have been "impossible physically, mentally to imagine that she could have got any distance at all".
A post mortem found Nora died of intestinal bleeding.
Her body was brought back to London where another post mortem examination was carried out. The Quoirins are awaiting the results of that investigation too.
Meabh told RTE today: "While a post mortem when it comes through may give us answers, and has already given us some basic answers around what caused Nóra's death, it doesn't explain any of how she could possibly have got to where she was found."
"We were incredibly touched by the support that we got.
"And in many ways, while you're completely cut off from the world in Malaysia, in that bubble of, frankly, hell, we could feel the love and the thoughts and the prayers of the world."
Nora, who was born with holoprosencephaly which means she had a smaller brain, vanished on August 3 .
Her disappearance sparked a massive 10-day search in the jungle that involved hundreds of people, helicopters, drones and sniffer dogs.
But the search came to a tragic end on Tuesday 13 August when her body was discovered.
The Quoirin family are now calling on the Malaysian authorities to carry out an inquest into Nora’s disappearance and death.