A hacker working for Mexico’s Sinaloa cartel obtained phone records and geolocation data of an FBI official in 2018 and used Mexico City’s surveillance system to track and expose U.S. informants—some of whom were later killed, according to a U.S. Department of Justice report released Thursday.

Surveillance Breach Tied to “El Chapo” Network

The hacker was linked to the criminal empire once led by Joaquín "El Chapo" Guzmán. By exploiting the phone number of an FBI assistant legal attaché based in Mexico City, the hacker accessed detailed call logs and real-time location data, the report stated.

Using this information, cartel operatives tapped into Mexico City's surveillance camera system to monitor the FBI official’s movements and identify associates—some of whom were FBI informants or cooperating witnesses.

Informants Tracked and Killed

The DOJ Inspector General’s audit said the cartel used the data “to intimidate and, in some instances, kill potential sources or cooperating witnesses.” Though names were withheld, the implications highlight a devastating intelligence breach.

U.S. officials confirmed that the case underscores the vulnerabilities created by the global explosion of digital surveillance technologies.

DOJ Urges Strategic Reform

The report recommended urgent improvements in how the FBI secures personnel data abroad, including increased training and controls. It also warned that the ease of accessing commercial phone and travel metadata allows even “less-sophisticated nations and criminal enterprises” to exploit these tools for lethal ends.

No arrests have been announced, and the FBI and U.S. Embassy in Mexico declined comment.