Border guards in the central province of Thanh Hoa have handed over to authorities in Laos four people who were caught earlier this week for the storage of 39,400 pills of methamphetamine.
Thao Giang Ho, 55, the first arrestee, was caught at the border carrying four meth pills on Monday afternoon.
The Vietnamese border guards then followed his traces to two houses and arrested his three accomplices.
Nang Chu Ho, 49, and her son Thao Bi Tho, 35, were arrested on the same day with 27,400 pills and 200 grams of heroin in their house in the Lao province of Hua Phan.
Authorities also seized nearly US$30,000.
Another search at the house of Chong Van Tho, 40, in the same evening also uncovered another 12,000 pills.
The drug bust was reportedly the biggest joint operation between Vietnam and Laos authorities. Authorities said they are expanding the investigation.