After high school in Yonkers (New York) gag spent a year in Paris and studied at the Sorbonne. Back in Ohio, he attended Miami University in Oxford, where he made in 1934 his university degree. After his studies he worked as a journalist for various newspapers. In 1960 he wrote a chapter of the book Candidates 1960, John F. Kennedy and began a career as a writer. His most famous novel is Seven Days in May of 1962, which was made into a film by John Frankenheimer. Knebel was 1935-1985 married four times and committed suicide in 1993 at his home in Hawaii.
- Seven Days in May (Seven Days in May, 1962), Scheffler Verlag, 1963
- From the night swallowed ( Vanished ), 1968 ), Molden Verlag, 1974
- Dollar Fiesta (The bottom line, 1975), Swiss publishing house, 1976
- The double wall ( Crossing in Berlin, 1981), Ullstein Verlag, 1986
- Baptism of fire ( Sabotage, 1986), Scherz Verlag, 1988