He gained notoriety due to the suspicious deaths of regime opponents: Who is Phao Siyanon?
He was appointed head of the Thai police force. He pursued a strict anti-Chinese policy during the purges of Thai Communists in 1952-53.
Phao Sriyanond (b. 1 March 1910, Siamese [now Thailand] – d. 21 November 1960, Geneva, Switzerland), director general of the Thai police force. He gained a strong position in the administration together with Luang Phibunsongkhram and Sarit Thanarat, and his attempt to seize power by creating a large armed force failed.
Police General Phao Siyanon (1 March 1910 – 21 November 1960) was a director general of Thailand's national police who was notorious for his excesses against political opponents. He eventually fled the country and died in exile.
He participated in the 1947 coup that brought Luang Phibunsongkhram back to power. During the new administration, he held various ministerial positions and was appointed head of the police organization. He pursued a strict anti-Chinese policy during the purges of Thai Communists in 1952-53.
It gained notoriety due to widespread allegations of corruption against police officers accused of opium smuggling and profiteering, and the suspicious deaths of regime opponents. In the early 1950s, together with Sarit, he strengthened his position against Phibunsongkhram. But his rivalry with Sarit led to a bloodless coup in 1957. After the coup, he was exiled together with Phibunsongkhram.
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Military-rule and military prominence in Thailand is a legacy of American imperialism
https://www.thaienquirer.com/15313/military-rule-and-military-prominence-in-thailand-is-a-legacy-of-american-imperialism/