He is then seen strapping it to a scooter and riding to a railway line about 10 minutes away.

The girl’s body was later found stuffed in a suitcase in grassy scrubland beside the track.

Carman allegedly told investigators that the girl had demanded money and tried to rob him before a struggle ensued, 9 News reported.

“I had my wallet open to get my money out, next thing I know there’s a knife in my face,” Carman claimed in a video recorded by police.

Thai investigators claim Carman “used one hand to grab the knife for self-defence, while his other hand gripped the woman’s neck”.

The investigator also claimed he had admitted to placing the woman’s body inside a bag, 9 News reported.

Video shows what police claim are scratch marks on Carman’s neck and arms.

Carman is also facing charges for allegedly abducting a minor aged under-18 for indecent purposes.

Murder can carry the death penalty or life in prison in Thailand.

The news channel reported that Australia’s Department of Foreign Affairs was aware of the arrest and was providing assistance to the man.