Malaysian police are analysing fingerprints from the cottage from which teenager Nora Quoirin went missing five days ago.
Her family have said they remain hopeful after police leading the investigation refused to rule out a “criminal element”.
Nora, who is from London and whose mother is from Belfast, disappeared from the Dusun forest eco-resort, in southern Negeri Sembilan state.
Her family released a statement expressing its “deepest gratitude” to the Royal Malaysia Police and others helping the search.
The force has analysed fingerprints found in a resort cottage from which Nora was reported missing, despite previously saying there were no initial signs of foul play.
The family’s statement said: “We would like to thank our embassies, the local community, and the staff here at the hotel and anyone else who has offered help to find Nora.
“We also welcome the assistance of the French, British and Irish police.
“We are completely overwhelmed by the support we have received from all over the world.”
Her parents, Meabh and Sebastien, an Irish-French couple, were “too upset to speak themselves at this time”, said the statement released on their behalf by the Lucie Blackman Trust, which helps crisis-struck British nationals overseas.
“This is extremely traumatic for the whole family,” it said.
The family, including Nora’s younger brother and sister, arrived at the resort about 40 miles south of Kuala Lumpur on Saturday.
They believe Nora, who has learning and developmental disabilities, was abducted.
The statement added: “We must remain hopeful.
“And we ask everyone to keep Nora in their thoughts, and to continue to support the ongoing search for her.
“Nora is still missing, and she is very vulnerable, and we need to do everything we can to bring her home.”
Deputy police chief Che Zakaria Othman said police have received the laboratory results of fingerprint samples taken from the Quoirin family’s accommodation.
Investigations are still ongoing to identify who the fingerprints belong to.
The prints were at an open window in a downstairs hall, not in the bedroom upstairs where Nora was sleeping with her siblings, he said.
Police added they were “not ruling out any possibility” and that believe Nora is still in the area.
The rescue operation involves more than 200 people working around the clock.
Nora’s aunt, has made an emotional appeal for help in locating her niece.
Éadaoin Agnew asked people to keep the 15-year-old, who disappeared in Malaysia on Sunday, in their thoughts.
Fighting back tears at one point, she said Nora’s disappearance had been “extremely traumatic for the whole family”.
“Nora is still missing. She is very vulnerable and we need to do everything we can to bring her home,” she said.
Malaysian police have also begun using recordings of Nora’s mother’s voice in the jungle around the holiday resort to try and draw the teenager back, in case she has wandered off.