SAN DIEGO (AP) — The government's case against two men accused of dissolving corpses in vats of acid for a Mexican drug gang hinges on flawed witness accounts, defense attorneys said Thursday. Jose Olivera Beritan, 38, and David Valencia, 41, are accused burning two strangled corpses in 55-gallon barrels of acid heated by slow-burning propane tanks. The killings occurred in a San Diego home in June 2007 in what authorities say was an unusually gruesome display of drug violence crossing the border from Mexico to the United States.