Sues used his GI Bill benefits to pay for acting lessons at the Pasadena Playhouse, where he performed, later making his Broadway debut in the stage play Tea and Sympathy, directed by Elia Kazan, which had a successful run in New York City beginning in 1953 [REF].
After Laugh-In, Sues portrayed Professor Moriarty onstage in Sherlock Holmes (opposite John Wood, and later Leonard Nimoy), which, according to Alan, was "one of my favorite roles, because it's so against type, and I loved the makeup".