An Australian man has been arrested in Thailand after the body of a 17-year-old Thai girl was discovered stuffed inside a suitcase and dumped near a railway line in Pattaya, in a case that has shocked both countries.According to ABC Australia, Simon Carman, 45, was arrested on Friday evening at Bangkok's Suvarnabhumi International Airport as he allegedly prepared to leave the country. Thai police claim the teenager, Tunchanok Donhomla, was last seen entering a hotel with Carman in the early hours of Thursday before she disappeared. Her friends reported her missing on Friday after being unable to contact her.Investigators later traced her movements to the hotel where Carman had been staying.

CCTV footage allegedly shows the Australian leaving the building with a large black suitcase, which police say matched the one in which the girl's body was later found. Carman has denied killing the teenager, while Thai authorities continue their investigation.

CCTV footage forms key evidence

Police say Tunchanok, believed to have been working in Pattaya's Beach Road entertainment district, was last seen with Carman shortly after 3.30am on Thursday.

According to The Guardian, surveillance footage allegedly captured the pair entering a hotel together before Carman emerged around 18 hours later dragging a large black suitcase.Officers claim he strapped the suitcase to the back of a motorcycle and rode towards a railway line, disappearing from CCTV coverage for about nine minutes before returning to the hotel without it. Later that night, police discovered the suitcase about 4km away near the railway tracks.

Inside was the naked body of the teenager, who had suffered severe facial injuries, bruising and bleeding from the mouth and nose, according to Pattaya police.Following the missing person's report on Friday afternoon, Thai authorities issued an airport watch notice and arrested Carman at Suvarnabhumi International Airport just hours later as he allegedly attempted to board a flight to Australia.

Murder charges filed as suspect denies allegations

According to Pattaya police, Carman has now been charged with murder, concealing a body and offences relating to taking a minor for indecent purposes.

Police Superintendent Colonel Anek Sarathongyu said officers also found scratch marks on the Australian's body that were consistent with a struggle."We believe he killed her, and he is being questioned on suspicion of murder," Sarathongyu told ABC Australia. Carman, however, denied responsibility, claiming the teenager left the hotel room while he was asleep.The Bangkok Post reported that Carman allegedly told investigators he acted in self-defence after an argument over payment escalated and the teenager threatened him with a knife. He allegedly claimed he grabbed her by the neck but insisted he had no intention of killing her.