An Arizona law enforcement officer who served as a spokeswoman for the state's Department of Public Safety was forced to resign on Monday after a federal investigation revealed she was an illegal immigrant.

The investigation was launched in August after Carmen Figueroa's brother, who serves in the Air Force, applied for a passport, triggering a red flag at the State Department.

It has since been revealed that Figueroa, a DPS employee for over a decade, had been told by her mother that she and her brother were born in the US, when in reality they had been born in the Mexican state of Sinaloa.

Figueroa was therefore ineligible to serve as a police officer, but it remains unclear if she knew the Social Security card and birth certificate she handed the DPS back in 2003 were forged.

"She was under the impression that she herself was an American citizen," DPS spokesperson Bart Graves told News 4 Tucson.

Figueroa, who rose through the ranks to become a criminal investigations detective and, for a time, the department's spokeswoman, was put on paid leave back in September before formally resigning on Monday.

Graves said Figueroa, who had an "exemplary record," would have been terminated had she not quit voluntarily.

Graves told the Associated Press his department was "absolutely having in-depth discussions right now to prevent this from happening again."

[screengrab via KVOA]