Karel Vas, a prosecutor who came to symbolize unlawful trials during the post-1948 communist takeover of Czechoslovakia, has died, a government institute said Monday. He was 96.

The Institute for the Study of Totalitarian Regimes announced Mr. Vas’s death but gave no details. Czech public television reported Mr. Vas died Nov. 10 in a home for retirees in Prague.

Mr. Vas was born March 20, 1916, in the city of Uzhorod in what is now Ukraine. He joined the Communist Party of Czechoslovakia at 17.

During World War II, he moved to the Soviet Union, where he began to collaborate with dictator Joseph Stalin’s much-feared secret police, known as NKVD.

Historians say Mr. 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, Mr. 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. Mr. Vas was accused of inserting a fake document into Pika’s file that served as evidence that he worked for British intelligence.

But Mr. Vas served no prison time after an appeals court canceled the verdict because of the statute of limitations.

— Associated Press