Jonath finished third behind George Saunders in the 100 yards event at the British 1933 AAA Championships.

[3][4][5] After the Los Angeles Games, Jonath stayed in the United States upon invitation from actresses Greta Garbo and Marlene Dietrich.

He was offered American citizenship and a university education, but his stepfather brought him back to Germany.

During World War II he fought as an SS officer on the Eastern Front; he was taken prisoner by the Soviet troops and then transferred to an American prisoner-of-war camp near Frankfurt.

After the war Jonath ran a petrol station and trained runners at FSV 1899 Frankfurt.