SAN FRANCISCO — From the mayor on down, a court-appointed investigator said Wednesday that Oakland officials mishandled, downplayed and ignored a far-reaching sexual misconduct scandal in the city's police department.

In a court filing, investigator Ed Swanson put most of the blame for the bungled probe on former police chief Sean Whent, who resigned under pressure last year. But Swanson also singled out Mayor Libby Schaaf for failing to monitor the case after she vowed dramatic reforms in the police department.

Schaaf declared in 2016 that her job was to run a "police department, not a frat house" and Swanson credited her with acting quickly when she was first informed of the scandal and a federal judge ordered an in-depth investigation.

But Swanson said in his report that she did not do enough after the investigation was over to determine why the police department did not investigate the case more thoroughly.

"Although they took the appropriate step of hiring an outside attorney to investigate this issue many months passed with no investigative progress, and there is no evidence city leaders pressed to ensure this troubling and important question was being answered," wrote Swanson, who was appointed by a federal judge who oversees the police department as part of a decades-old lawsuit settlement.

Schaaf's spokesman, Michael Hunt, did not immediately return a telephone message left Wednesday seeking comment.

Swanson's report faults police for failing to launch a serious investigation into a teenager's claims she had sex with as many as two dozen officers beginning when she was 16.

Criminal investigators initially closed their probe after a strained, two-hour interview with the victim, who gave muddled and conflicting accounts.

Swanson's report also faulted police internal affairs investigators for lackluster work. The victim was interviewed once on the phone. The report concluded that Whent was disinterested with the case from the start, setting the tone for his subordinates.

The city paid the victim almost $1 million to settle her legal claims. Seven current and former officers face criminal charges.

Whent retired under pressure in 2016 after news of the scandal emerged.

Whent's phone rang unanswered after the report was released.