Carman denied additional charges related to murder, moving or concealing a corpse and taking a minor for sexual purposes and claimed he acted in self-defense.
According to media reports, Carman told police he had agreed to pay Donholma 1,000 baht (£23, US$30, A$43) for sexual services, but when he returned to the apartment there was an argument and he only offered 500 baht.
Thai police told the Australian Broadcasting Corporation (ABC) that Karmando Donhomra claimed he “disappeared from the room” while he was sleeping.
In a video recorded while in custody, the suspect sent a message to Donholma’s family: “I’m sorry what happened to your daughter. It was something I had no control over.”
“I know you are very sad and upset… just like I am.”
He added, “Be sure to tell other women to be careful.”
Pattaya City police chief Colonel Anek Srathongyoo told ABC that Karman had fingernail scratches all over his body, consistent with a struggle, but denied killing her.
In another police video clip, Carman is seen being questioned about the scratches.
“I think it’s a spider. It always comes in here,” he replies.
Donhomla’s family told ABC she was an only child who lived with her father and stepmother in Kalasin province, about 480km northeast of Pattaya. The teenager, nicknamed Cake, told her parents she wanted to go on holiday with friends and traveled to Pattaya on June 16.
Her father Thongchai Donhomla said he was “deeply saddened” by his daughter’s death.
“My daughter didn’t have a mother, so whenever she wanted something, she found her own way and she always helped me,” he told a local reporter.
“We were scared. We just hoped it wouldn’t happen the way we feared. Now our eyes are swollen from crying,” said her stepmother, Oradee Bussarakum.
“I just want to execute him. I even asked the police if I could beat him or beat him,” she added.
If convicted of murder, Carman could face the death penalty.
