Los Angeles County Sheriff Lee Baca said the charges against 18 current and former sworn officers on allegations of jail misconduct mark a "sad day" for the department, but he denied suggestions that it represents a larger, institutional problem.

At a news conference Monday afternoon flanked by more than a dozen of his top aides, Baca said he and the department have fully cooperated with the FBI's investigation and "didn't hold anything back."

"Please know that I respect the criminal justice system and no one is above the law," Baca said.

LIVE CHAT: Discuss the indictments Tuesday at 9 a.m.

He later added: "I accept responsibility.... You don't see me retire from the job (or blame others)."

For the last 163 years, 99.9% of Sheriff's Department employees "have done outstanding work," Baca said, adding that he is confident that 99.9% remain on the "right track."

On Monday, federal officials unsealed four grand jury indictments and one criminal complaint alleging that 18 Sheriff's Department employees engaged in abuse and misconduct inside Los Angeles County jails.

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Charges in the indictments range from conspiracy and obstruction of justice to improperly arresting and searching visitors to the jails.

In announcing the arrests, U.S. Atty. Andre Birotte Jr. said the incidents "did not take place in a vacuum."

"In fact, they demonstrated behavior that had become institutionalized," he said in a statement.

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"The pattern of activity alleged in the obstruction of justice case shows how some members of the Sheriff’s Department considered themselves to be above the law. Instead of cooperating with the federal investigation to ensure that corrupt law enforcement officers would be brought to justice, the defendants in this case are accused of taking affirmative steps designed to ensure that light would not shine on illegal conduct that violated basic constitutional rights.”

But Baca denied that the problems were widespread.

"There is no institutional problem within the Sheriff’s Department when it comes to correcting itself," Baca said, adding that reforms have been widely reported on.

"The exceptions of force incidents — 14 or 15 under indictment ... is not an institutional number. So that's my answer."

Baca declined to answer detailed questions about the allegations, citing the ongoing investigation.

"I've been waiting for the particular information and now we have it," he said.

He also declined to answer questions about whether an inmate was hidden from the FBI.

Federal authorities allege that officials hampered the federal investigation after the Sheriff's Department discovered that an inmate was working as a federal informant.

The officials moved the inmate — identified only as AB in the indictment — and changed his name, even altering the department's internal inmate database to falsely say that he had been released, according to the indictment.