Vietnam's online sleuths step up to tackle true crime

Arrest of murder suspect in gruesome killing comes after netizens post findings online

- Nga Pham

In late November, Doan Van Sang, then deputy head of Market Management Team No. 4 in Lang Son province a mountainous area in the northeast near the border with China, about 160km from capital Hanoi - was arrested by the police.

On Dec 3, he was formally charged with murder and detained without bail pending further investigation.

The killing of Mr Nguyen Xuan Dat on Jan 25 gripped netizens for months with its gruesome nature as amateur web sleuths attempted to solve the mystery, going online with their findings.

This case in 2025 was unique in that highly graphic information and evidence circulated online for weeks before the police made an arrest.

As the facts stand, Sang, 57, first “met” the victim through social media around 2020, where they reportedly engaged in “distorted, deviant” conversations involving sexually morbid or perverse topics. In January 2025, Sang called Mr Dat to his workplace, where the murder took place. According to the authorities, Sang made significant efforts to clean the crime scene, destroy evidence and dispose of the body.

The 36-year-old victim, Mr Dat, had reportedly been away from his family home in northern Thai Binh now Hung Yen province for about 10 years, working as a labourer and fishmonger before his death.

Online reports and unofficial documents widely circulated during the investigation suggest Mr Dat had been active in extreme forums under aliases like “datbeheading”, where he had expressed a “death wish” and fantasies that included being beheaded and cannibalised. While rumours of cannibalism were widespread on social media, official law enforcement and local news reports do not corroborate these claims.