A man in Thailand allegedly lured his sister and father to a pond and drowned them in separate steel boxes over his unhappiness with his father.

The 35-year-old man, identified as Warut Datephumee, was arrested by Thai police after the bodies of his sister and father were discovered on Jan. 9, reported Thai media outlets Thai Examiner and Thaiger.

Warut subsequently confessed to the double murder, claiming that he was unhappy with how his father threatened to end their relationship and cut him off from his inheritance.

Locals alerted police

Locals in the Phang Khon district of Sakon Nakhon alerted the police after they spotted two metal boxes in Nong Lum Hin pond on Jan. 9.

Authorities arrived at the scene and retrieved the boxes, which were locked and tied with thick chains.

After cutting off the chains, they discovered two bodies, which were later identified as a 33-year-old woman Piangpen Datephumee and her 68-year-old father Prayat Datephumee — sister and father of Warut.

The initial autopsy showed that they died from a lack of oxygen, having been thrown into the pond while they were still alive. The steel contraptions were submerged 3 metres deep.

Warut was seen at the scene "behaving erratically" and was subsequently detained by the police for questioning.

Confessed to murders

Following his arrest, Warut initially denied any involvement in the deaths of his sister and father.

A psychiatric evaluation found no issues and Warut was also found to be drug-free.

However, after a prolonged interrogation, Warut eventually confessed to killing his sister and father out of anger at their constant disapproval of his actions and his father's frequent threats to cut him off from his inheritance.

Planned the murders meticulously

Warut informed the police that the metal boxes were specifically designed for his plan. For instance, they were designed with wheels so that they could be pushed into the pond.

He ordered the two metal boxes from a factory in the province, telling them that he needed the boxes for his YouTube videos.

Warut claimed that he brought his father and sister to the pond by announcing that he was going to start a fish farm.

He then showed them the boxes, claiming that he was going to use them for "special beds with sheets that would swell and become fluffy at body temperature".

Believing his words, his father and sister allegedly lay down inside. Warut then proceeded to lock them inside the boxes before he pushed them into the pond.

Motive for the murders

Warut claimed that repeated arguments with his father made him feel that he could not impress the man.

He explained that his father threatened to end their relationship and cut off the inheritance he was allegedly entitled to whenever they argued.

Stressed that he could not impress his father, he decided to kill his father, he claimed.

As for why he killed his sister as well, Warut claimed that she was autistic and always sided their father.

Claimed he committed the murders alone

Warut insisted he was conscious and sober when committing the crimes and was not under the influence of drugs or alcohol.

He also claimed that he committed the murders alone.

While the police have accepted his confession, they will continue to investigate if anyone else was involved, Thai media reported.

For intentionally killing another person, Warut might face the death penalty, life imprisonment or imprisonment between 15 to 20 years under Thailand's laws.

However, the penalty for murder of one's father is the death penalty.

Top photos from Sawangphangkhon Rescue Picture & News/ Facebook