Alfred Frauenknecht, 64, a Swiss engineer found guilty in 1971 of selling Mirage jet engine secrets to Israel. Frauenknecht was sentenced to 4 1/2 years in prison in what was then Switzerland’s biggest spy trial since World War II. At his trial, Frauenknecht, who was not Jewish, said he felt morally obliged to help the Jewish people after the 1967 Arab-Israeli Six-Day War. He said he was concerned that the Soviet Union was helping Egypt to rebuild its armed forces, while Israel was suffering from an arms embargo imposed by France after the war. The Israeli air force relied on French equipment for its Mirage jet fighter force. Frauenknecht was a senior engineer with the company that manufactured the Mirage jet fighter engines for the Swiss air force under license from the French company. He admitted receiving $200,000 from Israel for about 200,000 jet engine blueprints smuggled in crates. The case prompted the Swiss government to expel an Israeli military attache. In Aadorf, Switzerland, on Jan. 8 after a heart attack.