LOS ANGELES (CBSLA.com) — Former Los Angeles County Sheriff Lee Baca withdrew his guilty plea Monday to a federal corruption charge that he lied to federal agents who investigated inmate abuse at the Men’s Central Jail.

“I made this decision due to untruthful comments about my actions made by the court and the U.S. Attorney’s Office that are contradicted by evidence in this case,” Baca said. “While my future and my ability to defend myself depends on my Alzheimer’s disease, I need to set the record straight about me and the Los Angeles County Sheriff’s Department on misleading aspects of the federal investigation while I’m capable of doing this.”

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In February, Baca entered the guilty plea, which called for the former sheriff to serve no more than six months behind bars.

“For the peace of my family, to avoid a lengthy and expensive trial and to minimize the court drama associated with this case, several months ago I entered a guilty plea to one charge filed against me – be very clear, one charge,” Baca defiantly said outside the courthouse.

But U.S. District Court Judge Percy Anderson rejected the plea agreement two weeks ago after prosecutors said a six-month sentence was too lenient even though the 74-year-old is in the early stages of Alzheimer’s disease.

The judge said the deal “would trivialize the seriousness of the offenses.”

Federal prosecutors argued the county’s former top lawman deserves prison time for falsely telling investigators in 2013 that he was unaware that sheriff’s deputies were going to the home of an FBI agent to confront and threaten her over her role in the probe of corruption within the department.

“It’s one thing to lie to an assistant U.S. attorney,” Anderson said. “It’s another for the chief law enforcement officer of Los Angeles County to cover up abuse in Men’s Central Jail.”

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Baca’s attorney, Michael Zweiback, told the judge that both sides had failed to find a resolution that would not involve withdrawing the plea.

Prosecutors said they would file an updated indictment against Baca and call him back into court for arraignment.

Pretrial hearings have been set for Sept. 6 and 12.

A trial date was scheduled for Sept. 20 but is expected to be postponed.

Baca argued in court papers for a probationary sentence, claiming his medical condition and law enforcement career make him susceptible to abuse while in custody.

More than 20 members in the sheriff’s department have been convicted on charges ranging from assault to obstruction of justice. One of the defendants was former Undersheriff, Paul Tanaka, who was sentenced to five years in federal prison.

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Baca retired in 2014 at the height of the federal probe. He had been sheriff since December 1998.