Fr. Mullen has taught full time at St. John’s Seminary in Camarillo, California since 1999, when he completed his doctoral studies. A yearly speaker at the Religious Education Congress in Anaheim, CA, he has also lectured for the Little Rock Bible Study Summer Workshop, the Texas Catholic Conference, regional conferences in San Diego, Las Vegas, Reno, Boise, Fresco, Phoenix, Utah and San Diego. Ordained to the priesthood for the Archdiocese of Los Angeles, Fr. Mullen began ministry as a parish priest.