Muzio became a freelancer theater director in New York City, New York. In 1996, she was invited to Indiana University as a part of the continuing Ralph L. Collins Memorial Lecture Series, where she gave two lectures on directing stage plays. Notable theater credits are Approximating Mother at the Judith Anderson Theatre and Loving Daniel Boone at the Actor's Theatre of Louisville's 1991-1992 Humana Festival. On Broadway at the Roundabout Theatre, she also directed Candida, the 1993 revival of Fifteen Minute Hamlet, The Real Inspector Hound, and The Plays the Thing. Muzio also became a member of the Executive Board of the Society of Stage Directors and Choreographers and was awarded the Joe A. Callaway Award, as well as being nominated for an Outer Critics Circle Award for her direction of Other People's Money. Muzio also worked on a number of TV shows, including Criminal Minds, Brothers & Sisters, The Black Donnellys, The Closer, ER, Third Watch, Law & Order, Law & Order: Special Victims Unit, The Wire, and Oz.
Muzio directed the following episodes of Criminal Minds: