LOS ANGELES (KABC) -- Former Sheriff Leroy "Lee" Baca might be getting nervous right about now.
Retired Captain William "Tom" Carey, 57, officially changed his plea to guilty on Wednesday, becoming the highest-ranking Los Angeles County Sheriff's Department official to flip in the years-long federal investigation.
"Guilty," Carey stated under oath as he stood before Judge Percy Anderson alongside his defense attorney Andrew Stolper.
Carey cut a deal with prosecutors that requires total cooperation with law enforcement as they forge ahead in their investigation of corruption and inmate abuse inside county jails, which are run by the LASD.
Speculation is growing that Baca, who abruptly resigned in January 2014, could be in the crosshairs of federal prosecutors.
"We've seen in the investigation of this case that the prosecution has been trying to go as high as they can, even to the sheriff himself," said Laurie Levenson, a Loyola Law School professor and former federal prosecutor.
Carey's co-defendant, former LASD Undersheriff Paul Tanaka, goes on trial this November for his alleged role in the scheme to block the FBI investigation.
Carey and Tanaka had both placed Baca at high-level meetings during the operation to hide inmate-turned-FBI informant Anthony Brown in summer 2011.
Brown, a convicted felon who was awaiting trial for a series of armed robberies in downtown L.A., was recruited by the FBI in 2010. His mission was to report on potential wrongdoing by deputies inside Men's Central Jail.
In an exclusive interview with Eyewitness News, Brown described what he says happened after a deputy found the contraband cell phone smuggled to him behind bars by a corrupt deputy as part of an FBI sting.
"They whisked me middle of the night, take me out and hide me. So who are they hiding me from? The Feds," said Brown who is now serving 423 years to life in prison.
Seven former deputies, sergeants and lieutenants have already been sentenced to prison for their roles in the scheme that became known as "Operation Pandora's Box."
All seven are appealing the verdicts and remain free on bond.
Carey's plea deal means that three felony counts -- obstruction of justice, conspiracy to obstruct justice and one count of making false statements -- will be dismissed.
Carey pleaded guilty to one count of making another false statement, which points to what prosecutors say was the true motivation for hiding Brown from the FBI.
At the trial of Deputy James Sexton in May 2014, Carey testified that there was no other reason to move Brown other than for his own safety.
Carey now admits that was a lie because he "knew that the deputies ordered to stand guard over Inmate AB during this time were there, at least in part, so that the FBI could not have access to Inmate AB unless there was an order from co-defendant Tanaka or another LASD executive that would have allowed access."
Carey's cooperation agreement means he is likely to testify against Tanaka at his upcoming trial, although defense attorneys are sure to attack Carey's credibility now that he's admitted to previously lying on the witness stand.
Peter Eliasberg, legal director of the ACLU of Southern California, is watching the investigation closely and believes Carey's plea deal could spell trouble for Baca.
"This is further evidence that the government is very much interested in seeing whether it can make a case against the sheriff," Eliasberg told Eyewitness News.
Levenson and Eliasberg, however, both caution that it's too early to say if any information Carey provides could actually lead to Baca's indictment.
"Right now, we really don't have any indication that the federal authorities are going to charge Baca, but it's still a possibility," Levenson said. "He's not out of the woods yet, and that's why the defense is saying in Tanaka's case: Let's all hear from Baca! What does he have to hide?"
Levenson is referring to a motion filed by Tanaka's attorneys last week that asks the judge to grant Baca immunity so he can testify on Tanaka's behalf at the upcoming trial.
According to court documents filed by Tanaka's attorneys, federal prosecutors have refused to grant Baca immunity.
Baca's attorney, Brian Hershman, reportedly told Tanaka's attorney that while "no decision has been made to date, a 5th Amendment assertion by Mr. Baca is a strong possibility."
"Some might say why doesn't former Sheriff Baca just come forward and say these were renegade cops," Levenson said. "It's hard to know exactly how he would play this because if he says, 'These were renegade cops, I didn't know what was going on,' then you question why didn't he know? And then if he tries to save himself a little bit by saying, 'Well, I knew some of what was going on, but not enough' -- that's going to get him into a dicey area about whether he should be charged as well."
If Baca does, in fact, decide to plead the 5th, jurors are unlikely to ever learn about it in court.
"The problem for the defense, however, is the judge will not allow a witness to be called just to take the 5th in front of a jury," Levenson said. "Our laws say you have the right to exercise your 5th Amendment privilege against self-incrimination and that should not be used in any way in evidence. There may be so many reasons for that, that it's misleading for the jury to be considering that."
Baca did not return a call from Eyewitness News on Wednesday.
Carey faces a maximum of 5 years in prison, although sentencing guidelines referred to in the plea agreement suggest that a term of 10 to 16 months is what prosecutors are likely to recommend.
Carey's sentencing is set for Jan. 25, 2016.
Tanaka goes on trial in early November. He has pleaded not guilty.
Got a tip? Email Investigative Producer Lisa.Bartley@abc.com