The head of California’s powerful utility regulator announced to staff that she would be leaving her position at the end of the year, less than one year into a six-year term.

In her resignation letter, Marybel Batjer wrote that stepping down from the California Public Utilities Commission was a “difficult decision.” She did not specify a reason for her early departure, which stunned many observers.

Batjer wrote that in her last days in office she would “facilitate the transition of new leadership and better position the state for the reliability and safety challenges of this and subsequent summers and wildfire seasons.”

Batjer’s time in office has been beset by controversy. The regulator has struggled to contend with repeated deadly wildfires caused by the state’s largest utility, Pacific Gas & Electric. Even so, as PG&E emerged from bankruptcy, CPUC commissioners waived a $200 million fine for the utility’s neglect of electrical equipment. Since then, the CPUC and a federal judge have found that PG&E has continued to neglect its equipment, leading to more fires.

Batjer also was the subject of an investigation by ProPublica and the Bay City News Foundation last year, which found that the CPUC had not accounted for $200 million in funds that were supposed to be collected from utility companies for programs to assist the state’s deaf, blind and poor.

An audit released months after the investigation found that most of the money had been collected but the CPUC was not properly tracking what it was owed.

The news organizations’ investigation found that Batjer spearheaded the termination of the commission’s executive director, Alice Stebbins, who had warned of the agency’s problems tracking funds. The investigation found that Batjer and other commissioners had engaged in group texts discussing Stebbins’ employment that appeared to violate state open meeting law. Stebbins’ wrongful-termination suit and a separate suit over the alleged open meeting violations are still pending. The CPUC has said that Stebbins was fired for hiring and promoting unqualified colleagues.

Batjer came into the CPUC with no utility regulation experience. She started her career in the Reagan administration as a special assistant to the secretary of the Navy. After that she worked for years in the California state government before becoming an executive for the Mirage Casino in Las Vegas. She returned to California in the administration of then-Gov. Arnold Schwarzenegger and was later appointed to Gov. Jerry Brown’s cabinet.

A spokesperson for Gov. Gavin Newsom’s office said that a decision on her replacement will be made by the end of the year. Newsom’s office did not respond to questions about why Batjer was leaving the position.

“For decades, Marybel Batjer has helped tackle the most persistent challenges confronting Californians head-on,” Newsom said in a statement. “She is a passionate, smart and thoughtful leader and I’m grateful for her service to the State of California and wish her all the best in future endeavors.”