SANTA ANA, Calif. –Orange County Sheriff Michael S. Carona, the target of a federal corruption case, retired Monday to focus on defending himself against the charges.

”With a heavy heart, I therefore announce my retirement as sheriff, effective today,” Carona announced on the department’s Web site. His attorney, H. Dean Steward, confirmed the statement.

Calling it one of the most difficult decisions he has ever made, Carona said he believed it was the right time for him to retire from the nation’s fifth-largest sheriff’s department.

Carona, 52, was charged with conspiracy, mail fraud and witness tampering in October in a sweeping federal case that accuses him of pocketing nearly $700,000 in bribes and kickbacks. Prosecutors alleged he tried to enrich himself, his wife and a woman identified in the indictment as his mistress by accepting cash and gifts in exchange for political favors.

”This action will permit me to focus on vindicating my name and refuting the false charges which have been made against me and my wife,” Carona said in his statement.

Steward said Carona was not resigning, which could imply he was leaving because of political pressure or criticism. The Association of Orange County Deputy Sheriffs has demanded that Carona resign or take a leave of absence, saying that the charges against him were a distraction that had caused an ”erosion of public confidence” in the department.

”He’s not leaving because anyone is pushing him, he’s retiring for four or five different reasons,” Steward told The Associated Press. Steward said one of those reasons was Carona’s need to meet with his lawyers daily to prepare for his trial in June.

”He can’t do that and be sheriff at the same time,” Steward said.

A call to a sheriff’s department spokesman was not immediately returned.

Carona took 60 days of paid leave shortly after he was charged. He returned to the job a week ago. He earned about $199,000 before his leave.

During his week back on the job, Carona made arrangements for the department in preparation for his retirement, Steward said.

”He let the (county Board of Supervisors) know what was going on, do all the things necessary to actually retire,” the attorney said.

As a county employee for some three decades, Carona will be eligible for retirement benefits, Steward said.

Carona’s adviser Michael Schroeder said the sheriff decided to retire to settle questions about whether he could have a high-powered law firm representing him pro bono without violating state laws on gifts.

”The only way to resolve it … was for him to retire,” Schroeder said. ”It was a very difficult decision to make. We looked at every other way to do this.”

Schroeder denied that the sheriff’s retirement foreshadowed a plea deal.

”I can absolutely, categorically deny that this has anything to do with the underlying case,” Schroeder said. ”He intends to go to trial and he intends to be acquitted.”

Carona will receive a pension equal to his salary and benefits, Schroeder said.

Carona’s wife, Deborah, is charged with one count of conspiracy and his mistress, Debra Hoffman, one count of conspiracy, four counts of mail fraud and three counts of bankruptcy fraud in the case.

All three have pleaded not guilty.

Carona said he asked Undersheriff Jo Ann Galisky, who ran the department and its staff of 4,000 during his absence, to temporarily replace him until county supervisors appoint a successor, but she declined ”due to personal commitments.”

The board of supervisors was scheduled to meet Tuesday to discuss who will be appointed as interim sheriff through 2011, the end of Carona’s term.

”We’re going to take our time and do it right,” board chairman John Moorlach said.