In 2018, a hacker hired by the Mexican Sinaloa drug cartel run by the infamous kingpin Joaquín “El Chapo” Guzmán spied on the U.S. Embassy in Mexico City with the goal of identifying “people of interest” for the cartel to target and kill, according to a new U.S. government watchdog report.

Sometimes the surveillance state gets turned against itself. That seems to be what resulted in the unfortunate demise of a number of FBI informants, who were tracked by a hacker working for the Sinaloa cartel in Mexico, according to a recent report published by the U.S. Justice Department.

The hacker was able to break into the agent’s phone remotely and watch their incoming and outgoing calls, and even monitor the phone’s geolocation.