Encrypted chat service WhatsApp says it is cooperating with authorities as the search for missing Belgian backpacker Theo Hayez continues in Byron Bay.
Family of a Belgian backpacker, missing for weeks in northern NSW, hope information from an encrypted chat service will help authorities find the teenager.
NSW Police Force admit they are "baffled" by the disappearance of Theo Hayez, who was last seen leaving the Cheeky Monkey's bar in Byron Bay about 11pm on May 31 after earlier being captured on CCTV buying alcohol in a bottle shop.
His father Laurent Hayez arrived in the country last week and on Monday appeared at Tweed Heads police station to beg the public for help, saying his son was "in grave danger".
"I promised Theo's little brother that I would bring his brother home. Please, help me keep my promise to him," Mr Hayez asked through his tears.
Theo used encrypted service Whatsapp the night he disappeared and Mr Hayez asked for help in obtaining access to the messages.
WhatsApp has provided what information it has to NSW police.
However, the company is only able to access and disclose some information which can include a user's name, last seen date, IP address and basic information but not the content of the encrypted messages.
Theo had been preparing to return home after eight months travelling around Australia.
Homicide detectives are helping the investigation, along with Belgian authorities, but Superintendent David Roptell is holding out hope that Theo is alive.
Searches will continue with members of the community and multiple agencies scouring bushland, streets and beaches for any sign of the 18-year-old.
Anyone with information about this incident is urged to contact Crime Stoppers: 1800 333 000 or https://nsw.crimestoppers.com.au