Luy has assisted in hundreds of arrests over the past decade, with locals even nicknaming a HCMC roundabout after him. 

Nguyen Dinh Luy, 55, residing in Hiep Binh Phuoc Ward of Saigon's Thu Duc District, is team leader of a local neighborhood security watch.

Finishing his night shift at 5 a.m. on a July morning, instead of going home, Phuoc checked on a drug addict he had been keeping an eye on for ten days.

Wearing jeans, a T-shirt and jacket, Luy resembles a motorbike taxi driver and often gets accosted for business.

While on patrol, Phuoc once witnessed two helmet-less bikers receive a black package from a woman in an abandoned lot. When he intervened, one man threatened him with a knife, though he quickly wrestled the culprit to the ground as police arrived on the scene.

Luy goes out on patrol even when not on duty. Photo by VnExpress/Diep Phan.

"Apart from keeping his neighborhood safe and assisting local police, Luy actively pursues criminals himself," said Lieutenant Nguyen Ngoc Hai, police head of Hiep Binh Phuoc Ward.

Locals have grown to trust the unmasked vigilante.

"We call this area 'Luy Roundabout' because thanks to him, local security has greatly improved. No one can trick him," said Ly van Ha, 60, a motorbike taxi driver.

The 'passion' to fight crime hit Luy naturally after his bicycle got stolen in 1999 while visiting Binh Thanh District's Ba Chieu Market with his seven-year-old daughter.

Comforting his crying and distraught daughter, Luy promised himself he would bring those responsible to justice.

Three years later, Luy relocated to Thu Duc District where his partner set up shop as a fish vendor, getting to know his new neighborhood by working as a motorbike taxi driver.

According to Le Van Vuong, 68, a resident of Linh Trung Ward, the area near Binh Phuoc crossroads used to be rife with pickpockets and robbers. 

"He always told us to help victims of accidents or theft. To deal with the stubborn, Luy uses his fists," Vuong said, adding that once a policeman had to restrain him from treating suspected criminals too harshly.

In 2009, Luy was encouraged to join the neighborhood security force.

As the enemy of local gangsters, many threatening calls were made to his house. Under sustained threat, his family were forced to relocate on the grounds of safety.

Having foiled the plans of many criminals, Luy has been lucky to never suffer serious injury, thanks in part to his martial arts training.

"Luy is brave, agile, and unafraid of placing himself in harm's way," Lieutenant Hai said.

Ensuring community safety should be the task of every resident, according to Luy.

"No one forced me into this, God gave me the eyes to spot criminals, I cannot stand about and do nothing," Luy said with a smile.

"A caught drug trader once came to thank me, saying rehabilitation had cured him of addiction, and that he was training to become a truck driver to restart his life," Luy said.

Staying home for ten days after a criminal had pushed him from his bike, a determined Luy could not wait for his wounds to heal, venturing out onto the streets once more after an uplifting call to his daughter.

At the age of fifty, not as healthy as before, his courage remains undiminished.

"Previously, I could remember a license plate number for months, but my memory is slowly failing. I will keep giving criminals a hard time until I'm old and shaking," Luy maintained.

*All names have been changed to protect identities.