WATCH LIVE: Sheriff Lee Baca expected to announce retirement

L.A. County Sheriff Lee Baca is expected to announce his retirement at a 10 a.m. news conference outside department headquarters.

Baca, 71, told top officials in county government late Monday that he believes stepping down would help the department recover after several years of tumult and criticism, according to sources familiar with the conversations.

The expected announcement comes a month after federal prosecutors filed criminal charges against 18 current and former sheriff's deputies accused of beating jail inmates and visitors, trying to obstruct the FBI and other crimes following an investigation of corruption inside the nation's largest jail system.

Baca won office in 1998 after his rival, incumbent Sheriff Sherman Block, died days before the election. In the next three elections, Baca easily won in primaries against fields of lesser-known candidates, avoiding head-to-head runoff elections. By 2010, no one bothered to challenge him.

But recently Baca was coping not just with the FBI probe but searing criticism of his leadership from a blue-ribbon commission appointed by the Board of Supervisors to examine allegations of jail abuse.

Last year, the U.S. Department of Justice accused sheriff's deputies of engaging in widespread unlawful searches of homes, improper detentions and unreasonable force as Antelope Valley authorities conducted a systematic effort to discriminate against African Americans who received low-income subsidized housing.

The two outside investigations portrayed a troubled department sharply at odds with the vision Baca preached during his 15 years as sheriff. More recently, The Times also reported that the department had hired dozens of officers in 2010 despite background investigations that found they had committed significant misconduct.

Doubts were growing that the previously popular sheriff would be able to win a fifth term as sheriff while facing a challenge from his former top aide, Paul Tanaka, and retired Cmdr. Bob Olmsted. Baca's decision to retire stunned many both inside and outside the Sheriff's Department.