A British man was found dead in a Cambodian guest house, before another tourist found with him discharged himself from hospital and went missing.
He has been named as 34-year-old Martin Stephen Hale from County Down, in Northern Ireland.
It is understood a second man – also from Northern Ireland – was taken to hospital.
Named on social media as Dean McWilliams, he is understood to have discharged himself and briefly went missing.
His sister appealed for help tracking him down on social media, reports Belfast Live.
She posted on Facebook: “I’m not one for sharing my private life on Facebook but if this helps bring my brother back I’ll try anything.
“Dean was recently visiting a friend in Cambodia his friend sadly passed away and Dean ended up in intensive care.
“He is now missing we don’t know where he is or even if he is safe.
“Nobody has heard from him. He was last seen at Happy House Guesthouse in Phnom Penh Cambodia at 4am Sunday morning (Cambodian time).
“We’re all so worried and just desperate to bring him home safe.