The Board of Supervisors took Sheriff Alex Villanueva to task this week for a $63 million budget deficit, with the CEO citing escalating overtime as a driving factor.

The discussion came as the board approved $3 billion in additions to the countywide budget, which now totals $36 billion.

Supervisors Hilda Solis and Sheila Kuehl co-authored a motion calling for a hiring freeze on Sheriff’s Department administrative and clerical personnel, pushing for a deficit mitigation plan, and recommending an ‘’operational review’’ by the auditor-controller. The motion was unanimously approved.

CEO Sachi Hamai said the department’s deficit ballooned from $25 million to $62 million and then $90 million in just three months, taking the county budget team by surprise.

While the sheriff has done a good job of hiring new deputies—which had previously proven difficult—department overtime has grown even as new deputies are trained and sworn in, according to the CEO.

“There seems to be something going on with the overtime budget,’’ Hamai told the board.

The county advanced $16 million to reimburse costs related to the Woolsey Fire and gave the department another $11 million it had paid out on judgments and settlements, in order to reduce the deficit. Then it funded the deficit to close the books for the fiscal year, which ended June 30.

An administrative director for the department said that increasing workers’ compensation and retiree costs were part of the problem, but Hamai said the county was helping all departments fund those costs. She said she expected the auditor-controller’s review would turn up other factors, reiterating her concern about overtime.

The CEO said the sheriff had also failed to adjust expected revenues when he chose not to apply for certain federal or state grants and also may not have collected other revenues due.

“Decisions he makes really (do) have an impact in trying to control his budget,’’ Hamai said.

The CEO highlighted the fact that an estimated 43 cents of every dollar of locally generated tax revenue goes to fund the Sheriff’s Department.

Faced with questions from constituents about whether the board’s move was personal—given other battles between the supervisors and the sheriff on reinstating deputies, issues of transparency and deputy cliques—Kuehl said she had assured Villanueva in a meeting on Monday that it wasn’t.

“It’s important not to trivialize this action,’’ Kuehl said. “We are taking $63 million that could be (spent) somewhere else’’ to cover the department.

Villanueva said he was committed to working with the board, but urged the supervisors to fund the “true’’ cost of running his department, which he pegged at $3.9 billion, compared with funding of roughly $3.5 billion.

“We are currently the most understaffed law enforcement agency in the United States,’’ the sheriff told the board.

He cited a ratio of 0.9 deputies for every 1,000 residents, versus a national average of 2.5.

“Our operations are an open book,’’ Villanueva said, though he suggested that better work might be done in a less open forum and then left to allow his subordinates to answer the board’s questions.

Supervisors Kathryn Barger and Janice Hahn both noted that the department has a long history of outspending its overtime allocation.

“Overtime always blew the budget in the past,’’ Hahn said.

But the difference, Hamai insisted, is that in years past, the department was struggling to fill hundreds of new positions required to comply with various settlement agreements and changing state laws. Overtime was a natural consequence. Now hundreds of those jobs have been filled, but deputies continue to rack up overtime, she said.

Hahn offered an amendment calling for a look at the costs of running the department, seeming to imply that she would support more funding for Villanueva. The amendment was approved by a unanimous vote.

Barger raised concerns about compromising patrol service in unincorporated areas, though Hamai assured her that funding for those patrols came from a non-county source and would not be affected.