Police wrapped up their investigation and recommended 11 people be charged with murder and 11 others of disruption of public order.
Two others are still being hunted.
Pham Van Tuyen, 16, and Phan Van Tinh, 15, from Thuy Nguyen District were found dead with multiple injuries on June 18 last year. Authorities initially determined the cause could be a traffic accident.
However, at the scene, the police discovered weapons, motorcycle collision marks, and roadside tree stumps with unusual traces.
Based on security cameras, authorities found that before the bodies were discovered, there was a group of young men riding motorbikes at high speed.
In addition, at the funeral of the brothers, a number of strangers appeared to pay their respects.
Investigation results showed that a group of teenagers living in Thuy Nguyen District, when returning from Kinh Mon City of nearby Hai Duong province, saw the brothers on a motorbike.
They shouted at the pair, who were traveling home from work, and chased them before attacking them with iron pipes and spears.
Tuyen sped up and then crashed into a phoenix tree along the road. The attackers left the scene, leaving the two brothers to die.
At the time of the incident, Tuyen and Tinh were high-school grade students. They also worked as waiters at a snail shop in Hai Duong about 5 km from home.