Warning: This story contains graphic content

Pattaya: Australian Simon Peter Carman has pleaded not guilty to murdering a Thai teenager and hiding her body in a suitcase.

Carman, 45, is accused of picking up 17-year-old Thanchanok Donhomla for sex at about 3am on June 25 and taking her back to his unit on the outskirts of coastal Pattaya, about 150 kilometres south of Bangkok, before killing her and stuffing her slender frame into one of his suitcases.

He is charged with intentionally killing a person, concealing a body and two charges relating to taking a minor for indecent acts.

Carman made his first court appearance in Pattaya on Friday. Carman walked slowly into the courtroom shackled at the ankles and wrists, wearing maroon shorts and a brown T-shirt.

The judge suppressed this masthead and the ABC, the only media inside the courtroom, from reporting his emotional testimony in specific detail.

It has been reported that he had been on a walk near the beach and Thanchanok came back to his apartment. He has insisted the pair never had sex and claims Thanchanok asked for money as she was readying to leave. When all he produced was the equivalent of about $20, he says she grabbed a knife from his kitchen.

He pleaded not guilty to all charges. The case will return to court on October 12.

Carman has been detained since he was intercepted by immigration officials the night after the alleged murder, just minutes before boarding a flight to Australia at Bangkok’s Suvarnabhumi airport.

Much of his time in custody has been spent without legal representation.

Outside court, appearing gaunt, Carman said he had been assaulted twice in prison by inmates, lost about 30 kilograms, and had barely slept for months.

He said he had secured a lawyer only three weeks ago, despite, he claimed, having asked for one through the Australian embassy about two weeks after his arrest.

His application for bail was opposed by the prosecution on the grounds he was a flight risk, and the judge later refused bail.

In June, police released CCTV footage from Carman’s multi-tower complex in Jomtien that captured him doing laundry and picking up food before leaving with a suitcase later that night. More CCTV showed him driving through the streets with the suitcase strapped to the back of his rented scooter, before returning without it. Police later found Thanchanok’s concealed body in long grass near railway tracks.

The Ballarat-born, long-term resident of Thailand initially told the arresting officials at the airport that scratches on his body were the result of a fight with a friend, Pattaya City Police Colonel Anek Srathongyoo previously told this masthead.

But when he was confronted with the security footage, Srathongyoo said Carman admitted to unintentionally killing the 17-year-old in self-defence.