Stevens came into conflict with Senator Joseph McCarthy over a series of issues that ultimately led to the Army-McCarthy hearings of 1954. In the fall of 1953, McCarthy began an investigation into the United States Army Signal Corps laboratory at Fort Monmouth. McCarthy's aggressive questioning of army personnel was damaging to morale, but failed to reveal any sign of the "dangerous spies" that McCarthy alleged to exist. Next McCarthy investigated the case of Irving Peress, an Army dentist who had refused to answer questions in a loyalty-review questionnaire.