Over roughly two years in the Dallas area, Barber committed a series of murders that included acts of necrophilia, placing him among the more disturbing criminal cases in Texas history. He was ultimately convicted on three counts and executed nearly two decades after his crimes began.

His career bridged official military structures and clandestine violence in ways that proved especially difficult to confront or prosecute during El Salvador's civil war years. As a death squad organizer and political architect of the ARENA party, he helped shape both the extrajudicial killing apparatus and the formal right-wing opposition in a single country simultaneously. The UN Truth Commission's finding that he ordered the assassination of Archbishop Óscar Romero — shot dead while celebrating Mass — remains the act most associated with his name.