LOS ANGELES • The new head of the nation’s largest sheriff’s department vowed Saturday to usher in integrity and collaboration after his predecessor’s tenure was marked by clashes with public officials and allegations that ganglike groups of deputies ran amok within the agency.

Robert Luna took an oath of office during a noontime ceremony with family at his side. He officially begins his term as the 34th Los Angeles County sheriff next week, after winning election last month by a landslide.

The former police chief of Long Beach, Calif., will take charge of an agency with nearly 10,000 sworn deputies after the turbulent single term of Sheriff Alex Villanueva.