UCSF fired the head of its sexual harassment prevention office last spring after determining that she ordered an employee to falsify dates on complaints to make it appear that they were handled more efficiently, The Chronicle has learned.

The medical school confirmed that it fired Cristina Perez-Abelson in April after an investigation prompted by a whistle-blower found she also had instructed her staff to hide files from an auditor. She had been on paid leave since June 2016, according to the investigator’s report obtained through the California Public Records Act.

Perez-Abelson denied the findings and called the investigation process inadequate. In an interview, she painted a picture of an office overwhelmed by rising numbers of sexual harassment complaints, too few employees, and poor guidance from University of California headquarters on such key questions as when the official start date of a complaint should be.

UCSF said it had fired Perez-Abelson “for serious misconduct that included instructing her subordinates to withhold files from an auditor, falsify dates on case files in her office and backdate an investigation report. This action was taken after a thorough investigation into whistle-blower complaints.”

Perez-Abelson, an attorney, was hired in August 2013 and soon became director of UCSF’s Office for the Prevention of Harassment and Discrimination — just as the number of complaints at UCSF spiraled upward.

Nine UC Berkeley students and alumnae had just come forward, accusing campus officials of treating their sexual assault allegations too lightly, an action that precipitated an avalanche of sexual harassment complaints on university campuses across the country. Within months, dozens more students from UC alone had filed complaints with the U.S. Department of Education accusing administrators of mishandling their investigations.

Perez-Abelson said her predecessor at UCSF handled about 40 complaints a year. Her workload, she said, jumped to 250 a year.

“I don’t think anybody expected that to happen,” she said. “And I had no investigators for a very long time.”

Perez-Abelson investigated some of the cases. Others, she said, went to her associate director. Some went to outside investigators and some to human resources — which often bounced them right back because they were overworked, she said.

Meanwhile, UC changed its sexual harassment policy three times from February 2014 to January 2016.

“I would scream from the rooftops,” Perez-Abelson said, recalling her frustration. “There was no guidance in how to implement them.”

On June 10, 2016, someone called UC’s whistle-blower hotline and said Perez-Abelson had “repeatedly instructed staff to cover up and put inaccurate dates” on the cases they were investigating.

She was placed on leave a week later, the report says.

Staff members in the prevention department interviewed for the investigation called it a “regular practice of Perez-Abelson to delay assigning cases that came into the office. When assigned, the cases typically had a date in the file that was later than the date the complaint was actually received,” according to a copy of the investigative report.

One of the unnamed employees gave the example of a case involving a faculty member that remained unassigned on the director’s desk for about nine weeks. When the employee asked about it, Perez-Abelson replied, “Stop nagging,” the staff member told the investigator.

Date changes ranged from 24 hours to three months after the harassment complaint came in, according to the report. Employees told the investigator that it was done to make UC appear more efficient.

Several employees also said that files had been stashed under desks to prevent an auditor from seeing them. The investigator upheld both allegations.

Perez-Abelson denied concealing files and said they only set aside boxes that contained old and irrelevant files.

Asked by the investigator if she had instructed a staff member to inflate the number of cases her department closed each month, Perez-Abelson said, “absolutely not.”

She told The Chronicle that it was never clear what date an investigation should formally begin. Amid the confusion, she said, she’d had dates changed “to improve the record keeping.”

A spokeswoman for UC’s Office of the President, which sets policy for the 10 campuses, said that for years, campuses have had 60 days to conclude sexual harassment investigations — but she acknowledged that until February, it’s been “unclear how campuses marked the beginning of that investigation time frame.”

In February, UC clarified that investigations must begin on the date a notice letter is sent to the complainant and the accused, said Claire Doan, the spokeswoman.

Perez-Abelson said that having the dates altered on reports “was really correcting, not changing” them. “The allegation that I did it to shorten the time frame was just crazy. It’s nuts.” She said she had nothing to gain by suggesting that her department was more efficient than it was.

“I’m begging every week — I need additional staff! Look at my office! Stacks and stacks of cases!” she said.

“When you’re the person sitting across from the victim, and you’re listening to her complain — and you know you have no one to assign to the case — that wrenches your heart.”

UCSF said the campus has improved its handling of sexual harassment complaints by hiring more and better-trained staff, and a new director.

Nanette Asimov is a San Francisco Chronicle staff writer. Email: nasimov@sfchronicle.com Twitter: @NanetteAsimov