In a Monday letter to Corpus that was made public Thursday, Capt. Frank Dal Porto states that the command staff unanimously passed a vote of no confidence in her leadership over the weekend.
"This letter serves as the official communication to ensure that our position is clearly understood, and we formally request that you, the Undersheriff, and Victor Aenlle resign immediately," Dal Porto writes. "We hope that this matter is addressed with the seriousness it warrants, and we hope you will take the necessary actions to move forward."
County Supervisor Ray Mueller released the letter at a Thursday press conference, along with other documents he says further support accusations made against Corpus.
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Two weeks ago, the county released an independent report accusing Corpus of retaliating, abusing her power, using racist and homophobic language and having an inappropriate relationship with her chief of staff, Victor Aenlle.
Corpus denies all wrongdoing.
The nearly 400-page report was prompted by internal complaints. County supervisors commissioned the investigation in July, and it was conducted by retired Santa Clara County Judge LaDoris Cordell.
One of the most serious allegations made says that Corpus' executive team "improperly suppressed rifles." California Penal Code section 33410 makes it a felony to illegally possess a silencer or suppressor. However, there are exceptions for peace officers "when on duty and when the use of silencers is authorized by the agency and is within the course and scope of their duties."
Judge Cordell wrote that Aenlle improperly had "easy access" to suppressed rifles that were stored in the executive team's office. Aenlle was on staff as a salaried, fulltime civilian, but is not a peace officer.
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Mueller revealed another letter Thursday from Undersheriff Daniel Perea written on Nov. 14 to Corpus, detailing a "highly unusual set of circumstances where Victor Aenlle gave the undersheriff a request."
"This happened at a time when the board had already eliminated Victor Aenlle's position, meaning he had no authority to make this request," Mueller said.
In the letter, Perea tells Corpus that Aenlle expressed concern to him about the rifles stored in a safe in the executive team's office. Perea writes that Aenlle told him "this is how they are going to get me," and asked Perea if he could change the code to the safe.
"I did not take any of the actions he suggested," Perea writes. "I found the suggestion inappropriate."
In an exclusive interview with ABC7 News on Monday, Corpus said she has no plans of backing down and continuously denies all allegations.
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However, supervisors took action Tuesday to start a process that could potentially result in her removal from office, if approved by San Mateo County voters.
The board unanimously gave initial approval to an ordinance that would put a charter amendment on the ballot in a special election as early as March. It would ask voters whether to give the San Mateo County Board of Supervisors the power to remove an elected sheriff from office.
If voters approve the measure, supervisors would be able to remove an elected sheriff for cause, defined as: "means violation of any law related to the performance of sheriff's duties, flagrant or repeated neglect of the sheriff's duties, misappropriation of public funds, willful falsification of official statements or documents, or obstruction of any investigation into the conduct of a sheriff."
Before this charter amendment could go before voters in a potential special election, supervisors will have to also give a written notice to Corpus and give her an opportunity to speak to the public.
Read the full letter below or click here.