French era

In 1861, the French colonial government established a prison on the island to house prisoners who had committed especially severe crimes. After the turn of the century, the prison held an increasingly larger population of political prisoners. In 1954, it was turned over to the South Vietnamese government, who continued to use it for the same purpose. Notable prisoners held at Côn Sơn included Phan Châu Trinh from 1908-1911, Tôn Đức Thắng, Phạm Văn Đồng and Lê Đức Thọ in the 1930s,^[1] and Nguyễn An Ninh who died in the prison on 14 August 1943, possibly killed by his jailers for fear that he might be used politically by the Japanese.^[2]

Võ Thị Sáu was executed at the prison in 1952 (though she was imprisoned at the police post outside of the prison).^[3] Not far from the prison is Hàng Dương Cemetery, where some of the prisoners who died between 1941 and 1975 were buried.

Vietnam War

During the Vietnam War, prisoners who had been held at the prison in the 1960s and 70s were abused and tortured. In July 1970, two U.S. Congressional representatives, Augustus Hawkins and William Anderson, visited the prison. They were accompanied by Tom Harkin (then an aide), translator Don Luce, and USAID Office of Public Safety Director Frank Walton. When the delegation arrived at the prison, they departed from the planned tour, guided by a map drawn by a former detainee. The map led to the door of a building, which was opened from the inside by a guard when he heard the people outside the door talking. Inside they found prisoners were being shackled within cramped "tiger cages". Prisoners began crying out for water when the delegation walked in. They had sores and bruises, and some were mutilated. Harkin took photos of the scene. The photos were published in Life magazine on 17 July 1970.^[4]

French-made Tiger Cage

• Construction year: 1940
• Total area: 5.475 m²
• Each cell's area: 1.408 m²
• "Sunbathe" cell's area: 1.873 m²
• Empty space: 2.194 m²
• This cage consists of: 120 solitary confinement room (Divided into 2 regions, each regions has 60 cells)
• Basic characteristic: The top of each cells installed an iron grid and has a border between two regions which is a road for wardens.
• Besides, 60 cells have no ceiling, and are called "sunbathe" cells which are used to torture prisoners by making them "sunbathe" themselves.