Frederic Pryor, an American graduate student who was jailed in East Germany in 1961 on suspicion of espionage but later freed as part of the famous prisoner trade between the United States and Soviet Union dramatized in Steven Spielberg’s film “Bridge of Spies,” died on Sept. 2 at his home in Newtown Square, Pa. He was 86.

His son, Dan, confirmed the death.

By the summer of 1961, Mr. Pryor had been living in West Berlin for two years. Despite worsening Cold War tensions, he crossed regularly into East Berlin to interview economists and government officials for his doctoral thesis about the Soviet bloc’s foreign trade system.

While the Berlin Wall was being built, Mr. Pryor drove into East Berlin on Aug. 25, 1961. He tried to visit an engineer who had helped him on a research project, but when he reached her apartment she was gone.

The Stasi, East Germany’s secret police, which had been staking out her home, arrested Mr. Pryor for aiding in her escape to the West. After they found a copy of the thesis in his car, they charged him with being a spy.