Responsible for internal security , he also oversaw the Santebal -- the Khmer Rouge secret police .
After the Khmer Rouge took Phnom Penh in April 1975 , Son Sen was appointed Deputy Prime Minister with responsibility for Defense .
Responsible for internal security , Son Sen also oversaw the Santebal -- the Khmer Rouge secret police .
After the Khmer Rouge took Phnom Penh in April 1975 , Son Sen was appointed Deputy Prime Minister with responsibility for Defense .