Nguyen Tan Tai was found guilty of brutally murdering two volunteer members of the Tan Binh District Knights and injuring three other members last May.
Tai and his gang were trying to steal a motorbike parked on the street when the "knights" intervened and a fatal scuffle broke out.
The court sentenced Tai's accomplice, Nguyen Hoang Chau Phu, 24, to life imprisonment. Ngo Van Hung and his wife Trinh Thi Nhu were given four years in jail and a one-year suspended sentence respectively for harboring the murderer.
The indictment said Tai and Phu were "professional thieves" with criminal records who'd returned to old ways after serving previous sentences.
On May 13, Tai asked Phu to join him in carrying out a street robbery, but ran into a night patrol by the five vigilantes, dubbed the Tan Binh District Knights.
The vigilantes spotted the two thieves acting suspiciously and followed them.
When the duo tried to unlock a motorbike on Cach Mang Thang Tam Street, the vigilantes stepped in to capture them.
The thieves resisted and fought back, with Tai pulling a knife and stabbing two vigilantes who died on the spot.
After committing the crime, Tai called Hung and asked to stay at his home in Go Vap District for some days. Though Hung and his wife knew that Tai was the murderer being hunted by police, they didn’t report him and allowed him to stay.