Ho Chi Minh City investigators called for charges against 14 people undercover investigators tracked for months during the biggest drug smuggling case of 2013.
The defendants include Nguyen Thi Ngoc Suong, 36, who allegedly recruited her relatives to distribute drugs throughout the city in 2012.
Suong got the drugs from Tang Do Lien Huong, 44, who bought them from an unidentified smuggler in the north-central province of Nghe An, investigators said.
A team of narcotics police arrested the 14 defendants last year between January 19 and 30 following several months of undercover investigative work.
The team seized more than two kilograms of drugs, VND750 million (US$35,400) in cash and evidence related to the alleged smuggling of at least 3.5 kilograms of drugs.
The investigation was launched in November 2012 after police determined that low level dealers were buying drugs from someone in Ward 12 and 14 of District 8, which were considered major “black spots” on the city.
Dozens of plain clothes police posed as lottery ticket sellers and xe om (motorbike taxi) drivers to hunt for suspects.
They now say Tu and Suong sold drugs to Huong in various spots throughout the city and often visited a shop or a market stall, pretending to select goods, to conceal their secret transactions.
They even did deals in shopping center changing rooms to avoid police detection.
Vietnam has some of the world's toughest drug laws. Those convicted of smuggling more than 600 grams of heroin or more than 2.5 kilograms of methamphetamine face the death penalty.
The production or sale of 100 grams of heroin or 300 grams of other illegal narcotics is also punishable by death.