Matthew Winder, 31, was visiting the holiday island of Phuket and was reportedly due to arrive home on Tuesday, but was arrested on Monday morning for being "drunk and disorderly" outside a bar in Patong.
According to local reports, the 31-year-old from Newcastle was taken to Patong police station at about 5.45am and put into solitary confinement to "calm down". During that time, the guards allegedly stepped out for lunch and discovered the body when they returned.
Questions surround man's death
There are conflicting reports regarding the circumstances surrounding the man's death and an investigation is underway. But his heartbroken partner Ayla Varoxis is struggling to believe it was suicide as declared by Thai police.
"Foul play is in the mix and none of it makes sense," she told Daily Mail Australia. "He had all intentions of coming home to his family... he was doing better than his usual and everyone he loves will agree."
She said her partner had a "lion heart" and was a very generous man. "He was fierce, protective and strong," she said of Mr Winder.
Reports suggest the police guard on duty went for lunch at around 11.30am, leaving Mr Winder alone. When they returned they discovered his body. The sergeant went inside the cell to check his pulse, but he was already dead, according to the Bangkok Post.
Authorities claim there is CCTV vision showing Mr Winder "alone in the room and crying out for help" before his death but the claims are yet to be verified. An autopsy will now be performed, with Thai police confirming an investigation is underway. The Australian Embassy has also been made aware of the 31-year-old's death and is working to bring his remains home.
Do you have a story tip? Email: firstname.lastname@example.org.