SAN SALVADOR, El Salvador (AP) - Salvadoran police have arrested the mother-in-law of a U.S. Teamster gunned down in El Salvador last month, along with five other suspects, describing the slaying as a contract killing that was the result of a family dispute. Jose Gilberto Soto, 49, a U.S. citizen of Salvadoran origin from Cliffside Park, N.J., was shot in the back on Nov. 5 outside his family's house in Usulutan, 70 miles southeast of San Salvador. Soto had arrived in El Salvador on Oct. 30 to meet with the country's trade union leaders and port drivers. Rosa Elba Ortiz,...