Detweiler was born on February 15, 1919 in Trumbauersville, Pennsylvania. He studied at Quakertown High School. Detweiler was married to Jean Cahall from 1944 until his death in 2013. They had one daughter, Gina. Detweiler died on March 13, 2013 in his home in Easton, Maryland from natural causes, aged 94.