A court in the central province of Nghe An on Tuesday handed down the extra jail terms to 28 inmates for running a heroin ring while incarcerated, the Tuoi Tre newspaper reported.
According to the indictment, between December 2010 and November 2011, the gang smuggled more than 258 grams of heroin into Prison No. 3 in Tan Ky District.
The ringleader, Le Xuan Minh, 43, who is currently serving a nine-year jail term for robbery and violating the terms of his parole, was sentenced to 20 years imprisonment the highest among the 28 defendants in the Tuesday trial.
Other inmates received jail terms of between two and 15 years.
Prosecutors say the investigation into Minh's operation began on May 21, when guards caught him tossing 6.25 grams of heroin out of a cell window.
The officers searched the cell and seized four mobile phones, two of which belonged to Minh, and another 9 grams of heroin in the clothes of an inmate named Dang Minh Tho.
After prolonged interrogation, Minh confessed to throwing the heroin out the window to conceal his crime. He said the heroin had come from outside the prison and his gang of accomplices had smuggled the drugs in through a variety of means.
According to Minh's confession, inmates' wives routinely handed off heroin wrapped in condoms to their husbands during private visits. The inmates allegedly smuggled the heroin back to their cells concealed in their rectums.
Prosecutors say a number of individuals outside the prison assisted the gang in conducting its business. These accomplices would hurl packets of heroin over the walls at designated locations on the weekends.
Heroin was also routinely hidden in gifts presented to the inmates or buried under designated trees surrounding the prison so that Minh could dig it up during prison labor.
Investigators said that several of Minh's indicted cohorts did not use drugs prior to joining his gang. Once initiated, many shared syringes.
According to the indictment, Le Quoc Hung, Minh's accomplice, asked his family to open two bank accounts to support the business. Prisoners wishing to purchase heroin could do so by asking their families to transfer money into Hung's accounts.
Hung also had some outside accomplices collect money from the inmates' families.
Police say they have seized VND3.5 billion from Hung's accounts.
Hung was sentenced to eight years in prison on Tuesday.