The effort to spy on international officials adds to a sweeping espionage offensive in Mexico, where some of the country’s most prominent journalists, human rights lawyers and anticorruption activists have been the targets of the same surveillance technology. But the new evidence shows that the spying campaign went beyond the nation’s domestic critics.

It also swept up international officials who had been granted a status akin to diplomatic immunity as well as unprecedented access to investigate a case that has come to define the nation’s broken rule of law — and the legacy of its president, Enrique Peña Nieto.