An adopted son was arrested for allegedly killing his foster mother who was found chained to concrete dumbbells in a canal in Thailand.

Teerapat Sampaotong, 21, was detained at his home in Phuket on Tuesday after police linked him to the death of wealthy bar owner Kansiri Nasomboon, 51, who was found dead last Friday.

Fishermen discovered the woman's body floating in the Tha Yai canal in Phang Nga, two hours north of the bustling holiday island, on August 8. She was wearing a grey shirt and black shorts, with her neck chained to two concrete dumbbells weighing her down.

Following the grisly discovery, officers reviewed CCTV footage of the routes leading to the canal. They discovered Teerapat's black pickup truck allegedly taking the body and dumbbells to the channel before returning empty.

Authorities traced the vehicle to a residence in Phuket, where they found Teerapat with his biological mother. The black Isuzu pickup truck was also seized as evidence.

Teerapat allegedly admitted that he bludgeoned Kansiri to death with a dumbbell following an argument about investing in a host bar. He claimed she threatened him with a knife and he reportedly struck her in self-defense.

He said: 'I stayed at her house for one night before borrowing my parents' pickup truck to move the body. I told them I was just moving houses. I threw her corpse off the Sarasin Bridge heading out of Phuket. I did everything on my own.'

Teerapat's mother said he was studying and working in Phuket while residing with Kansiri as her adopted son. She did not believe her son was a murderer, adding the deceased had planned to give him two million baht (45,000 GBP) after making a house sale.

Police Colonel Prawit Engchuan, superintendent of Phuket Provincial Police's Investigation Division, said: 'The suspect claimed he planned and committed the act by himself. We handed him over to the inquiry officer of Khok Kloi Police Station for further legal action.'

Just days earlier, a Thai son allegedly confessed to murdering his mother and hiding her body in a cement-filled tub in Bangkok.

Tarn, 33, reportedly choked 73-year-old Jiranan to death after being enraged by her constant nagging.

He was said to have placed her corpse in the bathtub and entombed her in layers of cement and old clothes to mask the smell of decay. He continued living in the same house for around two weeks before walking into the Romklao Police Station on Monday, August 4, to turn himself in.

(1 GBP = 43.92 THB)