He attended Forest Lake High School and, after graduating, set out for New York to study acting at the American Musical and Dramatic Academy. Sieber made his television series debut in Two of a Kind (1998). In regional theatre, he has been involved in a string of world premiere musicals, including Randy Newman's "Faust" at La Jolla Playhouse, Bill C. Davis and Richard Adler's "Off-Key" at the George Street Playhouse and Larry Grossman's "Paper Moon" at Papermill Playhouse. For television, he has appeared in numerous commercials and in the daytime dramas, All My Children (1970) and Another World (1964).