Cab driver Uthai Phetseekaew told Bang Nam Jued Police sub-station of Muang district that he stopped to pick up a young man, aged 20-25 years, who asked him to open the boot so he could put some stuff in it.
The man then sat in the front passenger seat and told the driver to drop him in the Samae dam area in Bang Khun Thien area of Bangkok, according to a television news report.
Mr Uthai said when he arrived at Soi Samae dam the man asked him to stop the car, paid the fare on the meter, then got out and walked away.
Later, the driver realised that the man left behind the stuff he put in the boot. When he opened it to check he found a dead man stuffed in a black plastic bin. Mr Uthai said he searched for the passenger, but there was no sign of him. He then went to report the incident to police.
Police said the dead man was aged 20-25 years, dressed in a sleeveless black shirt and white jeans. His face had injuries inflicted by a sharp weapon. There was no indentification on the body, when had been wrapped in a blanket before put in the bin.
The police were trying to identify the body and the passenger.