Former Los Angeles County Sheriff Lee Baca this week withdrew his guilty plea to a federal corruption charge and will go to trial, with a court date tentatively set for September.

On Monday, Baca told U.S. District Judge Percy Anderson he wished to withdraw from an agreement in which the retired lawman had pleaded guilty to a false statements charge, which ordinarily carries a possible five-year prison sentence. Baca retired in 2014 after 16 years as sheriff.

The plea deal called for Baca to serve no more than six months behind bars.

With the ex-sheriff backing out of the deal, prosecutors said they would file an updated indictment against Baca and call him back into court for arraignment. Anderson set pretrial hearings for Sept. 6 and 12, and a Sept. 20 trial date, but that is expected to be postponed. Going into the hearing, Baca faced a choice of either withdrawing his guilty plea and proceeding to trial or being sentenced on the false statements charge.

Two weeks ago, Anderson rejected the plea deal that would have given Baca a maximum of six months in prison, saying the sentence was too lenient considering the retired lawman’s role in obstructing an FBI investigation into Los Angeles County jails. Anderson said the deal “would trivialize the seriousness of the offenses.”

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

Assistant U.S. Attorney Brandon Fox told the court that the government would file a new indictment “in the not too distant future.”

Zweiback said he expected that indictment to include a range of charges similar to those that were filed against former Undersheriff Paul Tanaka. Zweiback also indicated that his 74-year-old client faced a “significant illness issue” which could affect future proceedings. Baca has been diagnosed with the early stages of Alzheimer’s disease.

Anderson said at the July hearing that he would not accept a six-month prison sentence for a defendant who had played a key role in a wide-ranging obstruction attempt that did “substantial harm” to the community.

“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.”

To impose the penalty “would not address the gross abuse of the public’s trust,” the judge said, adding that such a punishment “understates the seriousness of the offense.”

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.

“He is suffering from Alzheimer’s, which has become advanced and it’s a very significant and concerning time for him about what he should do next,” Zweiback said today outside court.

Federal prosecutors countered that 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 involvement in the probe of corruption within the department.

The same year Baca committed the offense, he was named Sheriff of the Year by the National Sheriffs’ Association.

The rejected plea agreement—which one of Anderson’s colleagues on the federal bench recently called “troubling”—was widely seen as too lenient.

Hundreds of letters in support of probation for Baca were filed with the court.

Baca pleaded guilty Feb. 10 after denying for years that he had played any role in the wide-ranging scandal that stained the department and led to his retirement. He pleaded no contest to other allegations, including that in 2011 he directed subordinates to approach the FBI agent, stating that they should “do everything but put handcuffs” on her.

Prosecutors also accused Baca of lying about his involvement in hiding a jail inmate from FBI investigators. Baca, they alleged, ordered the inmate to be isolated, putting his second-in-command, Tanaka, in charge of executing the plan. Baca falsely claimed he was unaware that some of his subordinates had interrupted and ended an interview FBI agents were conducting with the inmate, who was working as a federal informant, prosecutors alleged in the court documents.

Tanaka’s 60-month prison sentence is the longest stretch of any defendant in the obstruction case. Seven former sheriff’s lieutenants, sergeants and deputies convicted of conspiracy and obstruction of justice received prison sentences ranging from 18 to 41 months. Their appeal was recently heard by the circuit court in Pasadena.