According to investigators, in mid-May, Ngo Hoang Phi ordered 10 silvered langurs at a price of VND 2 million (approximately USD 77) per animal for resale at a profit. After receiving a deposit from Phi, Do Khac Truong recruited Do Khac Cuong and Nguyen Tan Ben to enter the protected forest of Phu Quoc National Park carrying homemade firearms to hunt the animals.

Between May 14 and May 27, the group allegedly carried out multiple hunting trips, killing a total of eight silvered langurs and delivering them to Phi in exchange for VND 16 million (approximately USD 615). On May 29, Ngo Hoang Hau allegedly hunted an additional silvered langur and brought it home.

Police said officers caught Phi and Hau while they were processing the animals at a private residence. Authorities seized nine silvered langurs, either dead or partially butchered, one homemade firearm and other evidence related to the case.

After learning of the arrests, Truong, Cuong and Ben surrendered to police. Investigators said the three suspects cooperated with authorities, handed over firearms and other evidence, and returned all profits obtained from the sale of the animals.

Authorities determined that six of the nine confiscated animals were Indochinese silvered langurs, a species classified under Group IB, the highest level of protection for endangered, precious and rare wildlife under Vietnamese law.

The species is subject to strict conservation measures, with hunting, trading and possession prohibited except in limited circumstances permitted by law.