Police in Malaysia say that there was no suspicion of foul play in her death.
Nóra Quoirin died from intestinal damage likely caused by starvation and stress, say Malaysian police.
The authorities also confirmed that they did not find evidence of kidnapping or foul play.
After disappearing from her hotel room on 4 August, police believe that she's likely to have wandered off from a holiday cottage and got lost in the dense jungle. There was also no evidence "for the time being" to indicate she was a victim of kidnapping, police said.
The body of the teenager was discovered on Tuesday, more than a week after she disappeared during a two-week family holiday at a resort south of Kuala Lumpur.
At a press conference at the headquarters of Negeri Sembilan Police on Thursday (shortly before 2pm local time and 7am Irish time), police said that Nóra Quoirin died two to three days ago.
The cause of death, police said, was internal bleeding in her intestine, most likely caused by extreme stress or hunger.
In their most recent statement, the Quoirin family said their "hearts are broken" and paid tribute to their daughter as "the truest, most precious girl".
The full statement reads: "We would like to thank all the people that have been searching for Nóra and trying their best to find her. We thank the local people here and those far and wide for their prayers and support at this time. Nóra has brought people together, especially from France, Ireland, Britain and Malaysia. To all our friends and family at home, we can't thank you enough for all your love.
"Nóra is at the heart of our family. She is the truest, most precious girl and we love her infinitely. The cruelty of her being taken away is unbearable. Our hearts are broken. We will always love our Nóra."
