LOS ANGELES -- Former Los Angeles County Sheriff Lee Baca was convicted Wednesday of obstructing an FBI investigation into corrupt and violent guards who took bribes to smuggle contraband into the jails he ran and savagely beat inmates.

The trial, the second Baca faced after a jury last year deadlocked 11-1 in favor of acquittal on obstruction charges, cast a dark shadow over a distinguished 50-year law enforcement career that abruptly ended with his resignation in 2014 as the corruption investigation spread from rank-and-file deputies to his inner circle.

In addition to tarnishing his reputation as a policing innovator and jail reformer, the case threatened to put Baca, 74, who is in the early stages of Alzheimer’s disease, behind bars.

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He faces up to 20 years in prison, CBS Los Angeles reports.

“The former sheriff has now been held accountable for overseeing a widespread scheme to obstruct justice by issuing orders designed to protect a corrupt culture,” Acting U.S. Attorney Sandra R. Brown said in a statement. “As the Sheriff for Los Angeles County, Mr. Baca had a duty to uphold the law, a duty he utterly failed when he played an active role in undermining a federal investigation into illegal conduct at the jails. Today’s verdict shows that no one is above the law.”

Baca appeared to have escaped the fate of more than a dozen underlings indicted by federal prosecutors until a year ago, when he pleaded guilty to a single count of making false statements to federal authorities about what role he played in efforts to thwart the FBI.

A deal with prosecutors called for a sentence no greater than six months. When a judge rejected that as too lenient, Baca withdrew his guilty plea and prosecutors hit him with two additional charges of conspiracy and obstruction of justice.

The federal probe began in 2011 when Baca’s jail guards discovered an inmate with a contraband cellphone was acting as an FBI mole to record jail beatings and report what he witnessed.

Word quickly reached Baca, who convened a group to derail the investigation and ferret out more about what the FBI was focused on, prosecutors said.

Assistant U.S. Attorney Lizabeth Rhodes said during closing arguments that corruption in the nation’s largest jail system “started from the top and went all the way down.”

“When defendant Baca learned the FBI and a federal grand jury was investigating, he obstructed, and when he learned the FBI has turned its focus on him, he lied,” Rhodes said.

Baca’s subordinates hid the FBI informant from federal agents by moving him between different jails and booking him under fake names. Other department members tried to intimidate his FBI handler by threatening to arrest her.

Defense attorney Nathan Hochman didn’t dispute those facts but told jurors that prosecutors had presented no evidence Baca gave orders to obstruct the FBI.

Hochman was frustrated in efforts to present evidence of Baca’s diagnosis of Alzheimer’s.

There was no evidence Baca suffered from the condition during efforts to impede the FBI in 2011, and Judge Percy Anderson said mention of it could harm the prosecution by swaying jurors to sympathize with the ailing former lawman.

Former Los Angeles Sheriff Lee Baca, middle, leaves U.S. Court House building in Los Angeles on Wednesday, Feb. 10, 2016. AP

Anderson said it might be relevant to the lying charge because a psychiatrist was prepared to testify that Baca’s memory could have been impaired when he allegedly told prosecutors in 2013 that he was unaware of actions taken by deputies to thwart the investigation.

At the judge’s suggestion, prosecutors elected to first go forward with a trial on the charges of obstruction of justice and conspiracy to obstruct justice.

When that ended in mistrial in December, prosecutors said they would retry Baca on all three counts and take their chances with jurors hearing that Baca was now suffering from the early stages of the disease.

However, Anderson later barred the Alzheimer’s testimony, ruling it would be speculative and a waste of time.

The issue might have arisen if Baca testified, but he has sat silent throughout the proceedings, only occasionally conferring with his lawyers.

Hochman has only vaguely hinted at the issue, reminding jurors that Baca was 71 at the time of his interview with prosecutors and wasn’t lying, but had forgotten details. Hochman said much younger witnesses had also forgotten specifics in interviews and testimony.

In a series of rulings against Baca, Anderson also ordered him not to wear a ceremonial sheriff’s badge on his lapel that he wore during the first trial.

Baca headed the nation’s largest sheriff’s department for 15 years before his resignation.