They founded a Communist state with the name of Democratic Kampuchea, where any religion was forbidden and destruction of religious sites was frequent.

In May 1975, foreigners were expelled, including Catholic priests and religious, while natives were forced to work in rice fields and many of them were executed.

[3] French Bishop Yves Ramousse was at the head of the Cambodian Church when the Khmer Rouge took power.

On 14 April 1975, the Holy See appointed Salas as Coadjutor Bishop for the Apostolic Vicariate of Phnom Penh.

[3] On 1 May 2015, the Cambodian Catholic Church officially opened an inquiry into the presumed martyrdom of Joseph Chhmar Salas and another 33 persons who died during the time of the Khmer Rouge regime.