SEREMBAN, Malaysia — Malaysian rescuers will play a recording of the voice of the mother of a 15-year-old London girl who mysteriously disappeared from a forest resort, as the search entered a fifth day Thursday and her family made an emotional appeal for support.

Negeri Sembilan state police chief Mohamad Mat Yusop said police have already made voice recordings of Nora Anne Quoirin's mother and family members. He said rescuers will play the recordings over loudspeakers while combing the dense forest surrounding the Dusun eco-resort in the southern state.

"During the search, we will play the recordings as if her mother or the family is calling her. This is another method that we will try," he told a news conference, adding it has been used before in other cases.

Indigenous trackers already began calling out the girl's name early Thursday in their hunt. Armed members of the Senoi Praq, a special police team comprising indigenous tribes famed for their forest tracking skills, shouted "Nora!" as they waded through the hilly forest terrain.

Quoirin's family discovered her missing Sunday morning from the resort cottage and believes she was abducted. Police are treating her as a missing person but do not rule out a possible criminal element in her disappearance.

Mohamad said the rescue operation has been increased to more than 260 people working on shifts through the night. He said a police helicopter equipped with thermal imaging cameras joined the search Thursday morning to try and detect the girl, whom police believe is still in the vicinity of the resort.

Drones and police canine teams have also been deployed and divers have searched through the only river running through the hill but so far found nothing, he said. Police received some information from members of the public and are still investigating, he said, without giving details.

"We are still not giving up hope. Her family is also in strong spirits ... we pray hard that she will be found soon," he added.

Quoirin's parents are an Irish-French couple and have lived in London for about 20 years, according to the Lucie Blackman Trust, a British charity that supports people involved in crises overseas. Quoirin arrived with her family on Saturday for a two-week stay at the Dusun, a small resort located in a durian orchard next to a forest reserve 39 miles south of Kuala Lumpur.

Investigators have questioned 20 people so far and said a forensic team is analyzing fingerprints found in the cottage where the girl went missing.

Police have clarified that a window in the living room downstairs was left open, not one in the bedroom upstairs where the girl was sleeping with her two siblings. Her parents were in another room upstairs. Mohamad said the window was big enough for a person to squeeze through.

In a new video released by the Lucie Blackman Trust, the girl's aunt, Éadaoin Agnew, said the family was devastated but still hopeful.

"This is extremely traumatic for the whole family. Meabh and Sebastien are devastated and too upset to speak themselves at this time," she said, referring to the girl's parents.

"But 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," she added.