AUSTIN (KXAN) — The executive director of the Texas Department of Motor Vehicles, Whitney Brewster, resigned late Monday afternoon amid a series of KXAN investigations and turmoil over the state’s ongoing paper license plate problems, the TxDMV confirmed.

“It is with a heavy [heart] and mixed emotions that I write to you today to announce my departure,” Brewster said in an email. “Unfortunately, challenges and difficulties still face the state and organization. I understand the frustrations of our stakeholders to the problems and evolving situations we are working daily to resolve.”

Until the TxDMV board is able to find a replacement, Deputy Executive Director Shelly Mellott will serve as acting interim executive director.

Whitney Brewster at a recent TxDMV board meeting. (KXAN Photo/Richard Bowes)

The transition is “effective immediately,” the TxDMV announced in a news release.

“Often the hardest thing to do as a public servant leader is to step back and accept that you have done everything you can, and that it might be time to allow new leadership to take the reins and continue moving the agency successfully into the future.”

Brewster had come under fire in recent months for the agency’s handling of a temporary tag problem that has turned into a national security risk for law enforcement. In December, she faced tough questions about her agency’s handling of the temporary tag problem. For years, criminals have been able to access the TxDMV’s tag database by posing as car dealers. With a dealer’s license, they have been able to print and sell real temporary tags with fake information and phony vehicle identification numbers to all 50 states.

The news release announcing her departure makes no mention of the state’s paper tag problem, which is the biggest challenge the agency faces at the moment. Her resignation letter, however, does.

“Addressing temporary tag abuse has been our highest priority,” Brewster wrote in the Feb. 7 letter, noting her resignation was effective that day. “I am proud of the way the department has not shied away from this issue and has transparently and tirelessly worked with law makers, social media, law enforcement, stakeholders and the public to find remedies.”

Brewster said she had taken the “necessary reforms” based upon the “latitude given” to the agency. In leaving, she wrote, “the deck is clear for new leadership.”

Brewster’s profile was removed from the TxDMV’s website Monday. She grew up in Houston and was the second executive director to lead the agency since its inception in 2009, according to her former bio. Before coming to the TxDMV, she served for five years as director of Alaska’s DMV.

Brewster has been with the TxDMV since August 2012.