Haaretz, The New York Times, Jul 10, 2017

Women dressed to depict "La Llorana" or "The Weeping Woman" perform in a street theater act to remember the 43 missing students, in Mexico City, Saturday, March 4, 2017 Marco Ugarte/AP

The spying took place during what the investigators call a broad campaign of harassment and interference that prevented them from solving the haunting case of 43 students who disappeared after clashing with the police nearly three years ago.

[...] Still, it is hard to prove who ordered the spying. Even the manufacturer of the spyware, an Israeli cyberarms manufacturer called the NSO Group, says it cannot determine who, precisely, is behind specific hacking attempts using its technology.