The three unidentified men hired Nguyen Hung Manh, 53, to drive them from a border gate in Lang Son to Hanoi around 168 kilometers to the southwest last Thursday, authorities said.
When the taxi reached Bac Giang Province, 110 kilometers from Hanoi, they killed Manh and dumped his body in a river.
They escaped in the taxi but when they reached Phu Yen District in Son La, the vehicle broke down and they decided to walk.
When arrested they said they were trying to go to Myanmar.
They had planned the murder and robbery, they admitted.
Manh’s body was found on Monday in the Red River in Hanoi near the Chuong Duong Bridge.