KINGSVILLE, TEXAS — A public flashcard set on the study platform Quizlet contained security procedures and entrance codes for U.S. Customs and Border Protection facilities near Kingsville, Texas, before the set was made private on March 20. The set, titled "USBP Review," had been created in February and was accessible to anyone on the internet for approximately six weeks.

The flashcards included codes for specific facility entrances. One card asked "Checkpoint doors code?" and provided a four-digit combination as the answer. Another card asked for a specific gate's code and supplied an exact combination, and two additional gate codes were described in the same manner. The set also contained information about a 1,932-square-mile area of responsibility for the Kingsville workforce, spanning six county lines.

Beyond access codes, the flashcards described the agency's internal grid and zone organizational system. One card noted that a particular grid does not exist because of the structure of local highways. Another named the 11 CBP towers in the Kingsville area, while a separate card noted the abbreviated names of two towers and that a third tower had a shared area of responsibility.

A series of cards described immigration offenses including misuse of a passport, fraud or misuse of a visa, and fleeing from a checkpoint. Additional flashcards about voluntary return, expedited removal, and warrant of removal described forms to be filled out and reminded users to check a checklist on an "agents Resources Page" for accuracy. The final card detailed an internal system called "E3 BEST," which allows officers to record, investigate, and adjudicate secondary referrals at U.S. Border Patrol checkpoints by querying subjects and vehicles in multiple law enforcement databases and creating e3 Events for referrals resulting in an arrest.

The flashcard set was made private less than half an hour after a message was sent to a phone number potentially linked to the Quizlet user. An individual with the user's name was listed at an apartment address less than a mile from a Kingsville CBP facility. It has not been verified that the set was created by an active CBP agent or contractor. Basic keyword searches also revealed additional Quizlet sets that may have been created by new recruits to Department of Homeland Security agencies.

"This incident is being reviewed by CBP's Office of Professional Responsibility," a CBP spokesperson said. "We will not be getting ahead of this review. A review should not be taken as an indication of wrongdoing," the spokesperson added.

The Department of Homeland Security did not respond to a request for comment. Immigration and Customs Enforcement also did not respond to a request for comment.

"We take reports of sensitive or inappropriate content seriously and act promptly when content is found to violate our policies," a Quizlet spokesperson said. "We encourage anyone who encounters concerning material to report it directly from the flashcard set, class, or profile page, or to contact us so we can review and take appropriate action," the spokesperson added.