Once you build a surveillance system, you can’t control who will use it: A hacker working for the Sinaloa drug cartel was able to obtain an FBI official’s phone records and use Mexico City’s surveillance cameras to help track and kill the agency’s informants in 2018, according to a new US justice department report. The incident was disclosed in a justice department inspector general’s audit of the FBI’s efforts to mitigate the effects of “ubiquitous technical surveillance,” a term used to descr…