In 1984 Frisch returned to Zürich , where he would live for the rest of his life . In 1983 he began a relationship with his final life partner , Karen Pilliod . She was 25 years younger than he was . In 1987 they visited Moscow and together took part in the " Forum for a world liberated from atomic weapons " . After Frisch 's death Pilliod let it be known that between 1952 and 1958 Frisch had also had an affair with her mother , Madeleine Seigner-Besson . In March 1989 he was diagnosed with incurable colorectal cancer . In the same year , in the context of the Swiss Secret files scandal , it was discovered that the national security services had been illegally spying on Frisch ( as on many other Swiss citizens ) ever since he had attended the International Peace Congress at Wrocław/Breslau in 1948
International Peace Congress
World Congress of Intellectuals in Defense of Peace
Max Frisch