Authorities in Mexico Also Looking for Ariz. Authorities in Mexico have joined the search for a 6-year-old girl who disappeared from her Tucson, Ariz., home a week ago. Tucson Police said Friday that U.S. Marshals have been in touch with Mexican law enforcement officials who are helping to look for Isabel Mercedes Celis. Lt. Fabian Pacheco says police are looking at the possibility that Isabel could have been taken there because of Tucson's close proximity to the border. Officers in Mexico are checking hotels, bus terminals and other businesses. A photo of Isabel is being circulated as well. Isabel's parents say they last saw the first-grader in her bedroom the night of April 20, and they awoke the next morning to find her missing.