NOME, Alaska (AP) – The police chief who led efforts to audit more than 460 old sexual assault cases in Nome is quitting after 13 months on the job.

Chief Bob Estes will end his contract within the next 90 days.

Estes said the department has made improvements but noted the loss of personnel in the last year “continues to be a challenge on the backlog of cases.”

Nome officials didn’t immediately respond to an email seeking the number of officers who have quit in the last year.

An AP investigation into complaints by Alaska Native women from Nome and surrounding villages showed their reports of sexual assault were not investigated aggressively by the city’s police. From 2008 through 2017, data showed 8% of calls about sexual assaults against adults resulted in arrests with charges filed.