Mexican prosecutors say hooded gunmen on Wednesday killed the mayor of a small town just beyond the southern border of Tamaulipas state. He is the third mayor to have been slain in the last month, apparently by Mexico’s drug cartels. This comes a day after Jose Ives Soberon Tijerina, the head of public safety in Tamaulipas, resigned amid the escalation of violence in the northern Mexican state. Also on Tuesday, the bodies of two other officials were found – officials who were helping with the investigation of the 72 migrants who were massacred last month in the city of San...