SAN JOSE — Citing the intense personal attacks against him, the city’s independent police auditor has resigned, ending a short and tumultuous tenure and raising questions about the future of a vital civic watchdog role.

Aaron Zisser’s departure comes after the police union led a blistering, months-long campaign to oust him, pouncing on a string of missteps that the union insisted showed anti-police bias.

“I am enormously grateful to community leaders and advocates for their consistent and robust support,” Zisser wrote in a news release, citing part of his Thursday resignation letter to the city council. “Unfortunately, the extraordinary personal attacks on my office and my work have become a distraction from the important goals of reform and expanded oversight of the police sought by the public and community groups.”

He thanked his staff for its work to increase community outreach and help spur more comprehensive use-of-force evaluations and routine public disclosure of police shooting investigations, along with an array of other policy recommendations.

One of Zisser’s predecessors, LaDoris Cordell, who served as IPA from 2010 to 2015, said Zisser made the right move.

“I don’t think he did anything wrong during his tenure. I do believe there were some missteps that led to his being attacked by the POA,” she said, referring to the union. “The conflict he had with the POA was stalling the work of the office. Aaron took the high road by deciding to resign, and put the work of the office ahead of himself.”

Assistant auditor Shivaun Nurre, who has been with the office for over a decade, will head the office in the interim, as she has done with past vacancies.

Mayor Sam Liccardo, who had been critical of Zisser, was diplomatic in addressing the auditor’s departure.

“I’d like to thank Aaron for his service to our community, and for his hard work and commitment to police oversight. I respect his decision to step down and wish him well,” Liccardo said in a statement Friday. “We have a very talented team within the office led by our interim IPA Shivaun Nurre that will continue to push forward.”

The San Jose Police Officers’ Association issued a statement reiterating the stance that their problem was with Zisser specifically, and called the office “critically important to the city” and pledged to strengthen it.

“It is important to note that although we had serious legitimate questions about the judgment and actions of Mr. Zisser over the course of the last several months, the SJPOA never questioned the vital and essential role that the office of the IPA plays in the administration of justice for all San Jose residents,” the union statement reads.

That’s not good enough for community leaders who supported Zisser.

“The resignation of Independent Police Auditor Aaron Zisser after a heavy-handed attack campaign by the police union, SJPOA, raises major concerns for community members about the city’s commitment to police transparency and accountability,” leaders for People Acting in Community Together said in a statement Friday.

They characterized the political attacks on Zisser as veiled opposition to community demands for expanded reach for the IPA, including increased access to internal misconduct investigations — right now the office primarily audits citizen-initiated complaints — and officer-involved shooting probes.

Police Chief Eddie Garcia and the union responded by expressing support for exactly that expansion, but presented a cutting caveat: Not with Zisser at the helm.

But the community groups stood strong for both the expansion reforms and Zisser, and on Friday called for perhaps more powers for the police auditor.

“The SJPOA has claimed that they are supportive of increased independent oversight, just not with Aaron Zisser in the position. Now it is time for them to show it,” PACT said in its statement. “In order to overcome this setback and attract qualified candidates to the position, the mayor and city council must update the model to show that they do intend to have strong oversight comparable to that of other large cities.”

Unlike San Jose, cities like San Francisco and Oakland have civilian police commissions with authority to enforce discipline and reforms. The San Jose auditor was not given that authority when the office was created 25 years ago as a compromise between the city council, which wanted such a police commission, and the officers union. Police have pushed back against the idea of an overhaul, saying the department is not in a crisis that would necessitate it.

In his resignation letter, Zisser stated broad plans to continue “strengthening independent oversight around the region and nationally.”

“I will also continue to work for change in my own community, and I applaud the outstanding advocates and community leaders who work so hard to make important progress,” he wrote. “There is much work to be done to implement meaningful oversight and reform at SJPD.”

Since Zisser’s selection as IPA in September 2017, the police union was skeptical of him, albeit quietly at first. But then Zisser gave them an opening when he spurred controversy with an annual IPA audit report that suggested stark racial disparities in certain use-of-force cases, based only on a few incidents. The union escalated their campaign when Zisser’s office did not promptly alert SJPD about a man who allegedly threatened to shoot officers while making a police complaint.

He was later hounded for meeting with demonstrators before they rallied against police over a fatal 2016 officer-involved shooting, an event the union characterized as anti-police.

Garcia said those controversies were emblematic of broader trust and credibility issues, and that he believed Zisser did not sufficiently respect the department’s work, an assertion that Zisser pushed back on strongly.

“This entire episode has been unfortunate. This individual is not a right fit, and we were having issues that we’ve never had with any other auditor before,” Garcia said. “I am looking forward to once again working with an auditor that not only cares for this community, but has respect for the hard-working men and women of the SJPD.”

Police-accountability experts debated whether any of the acts warranted his departure, which other than a resignation would have required ten of the 11 council members to vote him out of his post.

“It is an existential threat on oversight,” Samuel Walker, a professor emeritus at the University of Nebraska, Omaha, and police oversight scholar, recently told this news organization. “It would be very damaging if he were removed assuming no official misconduct. (The city) will have a difficult time finding someone qualified and independent minded.”

Cordell said that she hopes the political cloud doesn’t thin the candidate pool for the next IPA.

“To those who might be interested in this job, they should step up and apply,” she said. “And take the lessons learned: If you are the IPA in San Jose, you have to be aware of the many stakeholders with different interests, and be able to walk that line.”

Walter Katz, Zisser’s immediate predecessor, voiced similar thoughts, saying unexpected turnover in police oversight, while rare, is a reality given the competing public and political forces in play. But he does not expect the controversy to carry over.

“(Turnover) can happen because this work can be extraordinarily difficult because of the broad range of stakeholders, who are looking to oversight to do fair and effective work,” he said. “When you have an office like the IPA which has a long history of stability, a relatively short period of turmoil won’t take away from the immense credit that the oversight community gives San Jose.”

Liccardo was similarly confident the city will be able to attract high-level candidates, and downplayed notions that the union will disproportionately affect the search.

“San Jose,” Liccardo said, “will continue to be a place where bright talented leaders in the field of police accountability will want to serve.”