Vowing to turn around the scandal-plagued Los Angeles County Sheriff’s Department, Jim McDonnell on Monday became the 32nd sheriff to lead the agency.

Sworn in by Los Angeles County District Attorney Jackie Lacey at downtown’s Kenneth Hahn Hall of Administration, McDonnell used his 15-minute speech to both inspire his officers and reassure a skeptical public.

He spoke of the “uncertainty and trauma” surrounding the department and talked of restoring “integrity, accountability and service.”

“You have been through a civil war that has torn this department apart,” McDonnell said, his comments directed at the department’s more than 18,000 officers and staff.

• VIDEO: McDonnell promises transparency

McDonnell inherits an agency that’s been under federal investigation over abuse and gang-like cliques of rogue officers. More than a dozen officers and one-time officers were indicted last December after an FBI investigation into alleged inmate abuse.

Amid scrutiny, Sheriff Lee Baca stepped down in January.

At Monday’s swearing-in ceremony, McDonnell vowed to “close the door on divisions and factions” in the department. “I’m telling you, as of today, those days are gone,” he said.

He also said he plans to review the agency’s management “to ensure all of our leaders and senior managers are in the right seats.”

The Sheriff’s Department operates the county’s jail system and helps patrol transit lines, parks, hospitals and county buildings throughout the region.

McDonnell recently served as chief of the Long Beach Police Department. He also served at the Los Angeles Police Department, where he was second in command under then-chief William Bratton.

More recently, he was a member of the Citizens’ Commission on Jail Violence.