EmMONTEREY PARK  (AP) — Embattled Los Angeles County Sheriff Lee Baca announced his retirement Tuesday amid federal investigations that have targeted abuses in his jails and discrimination against minorities in one of the communities his deputies patrol.

Baca said he would step down at the end of the month and wouldn't seek re-election because he was concerned about the "negative perception" the upcoming campaign would create concerning the nation's largest sheriff's department.

"I didn't want to have to enter a campaign that would be full of negative, contentious politicking," said Baca, 71, in an emotional statement outside sheriff's headquarters.

Baca spent 48 years in the Sheriff's Department and became the first Hispanic-American to hold the top post. He liked talking about his job, traveling the world and even went on uniformed patrol a few years ago to try and save the department from paying overtime.

He said it was time to step aside and give someone else a chance.

"I don't see myself as the future, I see myself as part of the past," he said.

Last month, 18 current and former sheriff's deputies were indicted for alleged crimes that included beating inmates and jail visitors, falsifying reports, and trying to obstruct an FBI probe of the nation's largest jail system.

Federal prosecutors said the charges showed that some sheriff's employees thought they were above the law and exhibited behavior that had become institutionalized.

Baca sidestepped questions Tuesday about whether he was worried that he might be indicted as part of the federal probe but acknowledged more of his employees might face charges.

"I'm not afraid of reality. I'm only afraid of people who don't tell the truth," he said.

Baca had weathered other controversies involving his department, but the indictments came as the strongest challenge to his legacy. The retirement announcement came as a surprise less than a month after Baca defiantly said the criminal investigation wouldn't drive him from office. He said he began thinking about retirement over the past weekend.

"I don't think anyone expected this," Los Angeles County Supervisor Don Knabe said. "We're all caught a bit off guard."

Because Baca is not serving out his term the five-member Board of Supervisors will be tasked with choosing an interim sheriff. Baca recommended Assistant Sheriff Terri McDonald.

Assistant Sheriff Todd Rogers said that he plans to run for the office. Baca's departure was premature but the department's leadership needs a change, Rogers said. Several others have said they would challenge Baca including two former underlings.

Baca has acknowledged mistakes while strongly defending his department and distancing himself personally from allegations of misconduct.

The sheriff said he made improvements, including creating a database to track inmate complaints. He has also hired a new head of custody and rearranged his command staff.

The American Civil Liberties Union sued the Sheriff's Department in 2012 saying Baca and his top commanders had condoned violence against inmates. The organization released a report documenting more than 70 cases of misconduct by deputies.

A federal jury in October found Baca personally liable for $100,000 for failing to stop inmate abuse by deputies in Men's Central Jail in a case brought by a man who said he was severely beaten while awaiting trial.

Last year a Justice Department investigation found deputies made unconstitutional stops, searches and seizures, and used excessive force against blacks and Latinos in the Antelope Valley on the outskirts of the county. Baca disputed the findings but said he had instituted reforms.

Baca was criticized in 2007 when he ordered Paris Hilton released from jail under house arrest after serving only a few days of a multi-week sentence for driving-related offenses. The sheriff said the socialite developed psychological problems, but a judge put her back behind bars for another 2 1/2 weeks. The case also drew attention to the overcrowded jail system.

A year earlier, Baca had to defend his department's handling of Mel Gibson's drunken driving arrest in Malibu, rejecting claims that deputies tried to cover up anti-Semitic comments made by the actor who had helped a charity organization for the Sheriff's Department.

The department also faced recent scrutiny over hiring and announced it was reforming hiring practices last month after it was disclosed that 80 deputies had criminal convictions, histories of misconduct or other problem backgrounds. It also gave preferential hiring treatment to friends and relatives of its employees under a special "Friends of the Sheriff" program that allowed top officials to lobby on behalf of applicants, the Los Angeles Times reported.

First elected in 1998 when his incumbent opponent Sherman Block died days before the vote, Baca was re-elected to a fourth term in 2010 and remained a popular figure for much of his time in office. Baca, an avid runner who estimates he's logged 70,000 miles, believes the only reason he kept getting re-elected was because he "never got away from the people."

Less than a year ago he was picked as the nation's sheriff of the year by the National Sheriff's Association, which cited his providing educational opportunities for inmates and efforts to work with religious groups.

The group also noted the vast size of the Sheriff's Department and the relatively low crime rates in areas patrolled by deputies.

The Los Angeles County Sheriff's Department is the largest in the United States, with a staff of 18,000 and a budget of $2.5 billion.