College Park Mayor Patrick Wojahn, a long-serving public official and advocate for environmental and social justice issues in his Maryland city, was arrested Thursday morning and has been charged with 56 counts of possession and distribution of child pornography. Wojahn, 47, had been mayor of College Park, home to the University of Maryland campus, for seven years and served on the city council for eight years before that. He resigned Wednesday night ahead of the arrest, the city said in a statement.