The Institute for the Study of Totalitarian Regimes announced Vas' death but gave no details. Czech public television reported Vas died on Saturday in a home for retirees in Prague where he had lived.
Vas was born March 20, 1916, in the city of Uzhorod in what is now Ukraine. He joined the Communist Party of Czechoslovakia at age 17.
During World War II, he moved to the Soviet Union where he began to collaborate with dictator Josef Stalin's much-feared secret police, known as NKVD.
Historians say Vas one of the state prosecutors who played a key role in show trials that used fabricated evidence to hand out death sentences to opponents of the communist regime in Czechoslovakia.
In 2001, Vas was sentenced to seven years in prison for his role in the case of a leading anti-Nazi fighter, Gen. Heliodor Pika, who was executed in 1949. Vas was accused of inserting a fake document into Pika's file that served as evidence that he worked for British intelligence.
But he escaped prison time because an appeals court canceled the verdict due to the statute of limitations.