MEXICO CITY (AP) — Search dogs led authorities to the grisly discovery of four clandestine graves containing at least 33 bodies in a sugarcane field in Mexico's Pacific coast state of Nayarit and officials said Wednesday the killings were likely linked to the drug trade. The graves were found in the township of Xalisco, which has long been the home base of a black-tar heroin trafficking ring that supplied the U.S.