Catherine Lester, director of the city's Human Services Department for the past three years, will step down to return to her family in Toronto, Canada, the mayor's office announced Friday.
"This decision was both difficult and personal, and I appreciate the support of the mayor and of my colleagues," Lester said in a statement Friday.
HSD deputy director Jason Johnson will serve as acting director. Mayor Jenny Durkan said she'll make a final decision on a permanent hire after regional homelessness task force One Table's recommendations in May.
Lester took the helm at HSD in 2015 under former mayor Ed Murray after four years working at the department. Durkan said her "tenacity and laser-like focus on results" helped domestic violence victims, youth, seniors, and other vulnerable people experiencing homelessness.
Under her time at HSD, the city also ramped up funding for homeless services, spending $64 million a year, and faced criticisms about its homeless encampment policies.
"She leads a department that is addressing our city's most urgent challenge, and following her departure, I know Jason will continue HSD's important work to move people out of tents, shelters, and transitional housing into permanent homes."
Her resignation leaves the city searching for a key player in how the city responds to the homelessness crisis at a critical time. Nearly 40 homeless deaths were referred to the King County Medical Examiner's Office in the first two months this year.