Phao was promoted to the position of director of the police in 1951, by which time he had become one of the country's all-powerful triumvirate. A client of the CIA, Phao received funds and hardware to build his personal fortune, as well as to turn the police into an alternative force to oppose his military rival, Sarit Thanarat.
Phao established an intimate circle of police officers, known generally as the "Knights of the Diamond Ring", which was notorious for its treatment of opponents of the government and the police generals - even resorting to assassination and murder. Their crimes were many:
* In March 1949, three MPs from Isaan and an associate, all one-time disciples of the exiled Pridi, were arrested on charges of treason. They were shot dead by their police escort while supposedly being transferred from one jail to another.
* On December 12, 1952, Tiang Sirikhanth - MP for Sakon Nakhon, a leading Seri Thai member, and an opponent of the government - was arrested with four of his associates. They were murdered (allegedly by strangulation in a police station) and their bodies burned in a forest in Kanchanaburi Province.
* A successful newspaper publisher, Ari Liwara, refused to sell out to Phao and was killed in March 1953.
* In 1954 Phon Malithong, MP for Samut Sakhon who provided evidence of corruption against Phao in Parliament, was in found tied to a concrete pier in the Chao Phraya River, having first been strangled.
Phao was extremely wealthy. He demanded protection money from businessmen, rigged the gold exchange, and blackmailed corporations into giving him huge shareholdings. He also profited greatly from the opium trade.
Police units transferred opium from the poppy fields of the Golden Triangle to Bangkok, ready to be exported. Trucks, planes, and boats which had been supplied to the police by the CIA, were instead used to move opium, which the police carefully guarded.