Known for building and running a criminal enterprise revolving around gambling dens, hotels, racketeering, extortion, loan sharking and restaurants that fronted for brothels, during his heyday, Năm Cam was considered one of the most powerful mob bosses in Vietnam, and was said to have attained influence that even extended into the ranks of Vietnam's Communist Party which he used to his advantage by bribing law enforcement and government officials to protect his lucrative enterprise and cover up his murders of other criminal rivals in Saigon that challenged his reign.

His downfall however came during a gang feud with another notorious female gangster from the northern city of Haiphong, Dung Hà who was considered one of the two great powers of the Vietnamese underworld alongside Năm Cam.

[7] Later, Đại Cathay and Bảy Sy, who was Năm Cam's brother-in-law were arrested as a result of South Vietnam's government campaign against crime in August 1966.

After that, Hiếu Trọc saved young Năm Cam's life and put him into the position of military logistics staff of the 313th Company of the Armed Forces in the South Vietnamese army.

[8] With his experience of being a ringleader, Năm Cam was regarded as being high skilled and sophisticated in his orders and guidance towards his followers, making sure to leave as little as evidence as possible by creating alibis for his crimes and directing his brothers only through the use of secret signals.

Dung Hà, a reputed female gangster from Haiphong in northern Vietnam, moved south to Ho Chi Minh City, to join forces with Năm Cam, who hoped to get her to serve as his emissary in expanding his casinos in the north.

[4][9] On June 4, 2003, Năm Cam was convicted for ordering the assassination of Dung Hà and bribing state officials to protect his criminal network and was sentenced to death by the court.

His co-defendants include two expelled members of the Communist Party's powerful Central Committee, 13 senior police officers, three former prosecutors and three state journalists.

Others who were also on trial included Năm Cam's first wife Phan Thị Trúc, who was charged with and found guilty of bribery, loan sharking and sheltering criminals.

The opening of the trial was broadcast live on national television, with the mafia leader Năm Cam being filmed with handcuffs on and was shown dressed in a black-striped prison uniform during the court proceedings.

[2] The case attracted unprecedented national attention from the Vietnamese public, such as when a crowd of over 500 people waited outside of the courtroom all for a chance to get a glimpse of the infamous mafia boss.

Some foreign observers, like Carl Thayer believed that the trial and conviction of Năm Cam and his men was a step in a positive direction, showing that the Vietnamese government was willing to put forth an effort to curb political corruption within the country.

[2] Subsequently, former Ho Chi Minh City police chief (1996–2001), Bùi Quốc Huy, was found guilty of negligence for enabling mafia boss Năm Cam to carry out his illegal operations.

Trần Mai Hạnh, the former head of state radio, and Phạm Sỹ Chiến, a former deputy national chief prosecutor, were both found guilty of receiving various bribes from Năm Cam, which included an Omega watch and a stereo.