COLUMBIA — Less than a month after news of Gov. Mark Sanford's extramarital affair broke, his most visible employee has announced Friday that he is leaving for opportunities in the private sector.

Sanford's communications director Joel Sawyer said he will leave the office effective Aug. 5. Ben Fox, the governor's Cabinet director, will become press secretary.

"It's truly been an honor to serve both Mark and the people of South Carolina for the past six and a half years," Sawyer said in a written statement. "This has been one of the most difficult decisions I've ever had to make, because I have and will continue to be such an ardent supporter of what this Administration is working to accomplish. I firmly believe that despite recent events, great things to move our state forward can be done during the remaining 18 months of this Administration.

"The public nature of my job might lead some to speculate about my reasons for leaving, but I want to be crystal clear that my departure is purely about what's best for me and my family on a personal and financial level. I wish Mark and the rest of my talented and dedicated colleagues the best."

Sanford admitted June 24 that he had a yearlong extramarital affair with an Argentine woman. The governor said he won't resign. A criminal investigation found that Sanford did not misuse public money on the affair, but the governor decided to repay the state $3,300 for a 2008 commerce trip to Argentina during which time he admitted to seeing his mistress.

The governor has been away for most of the week with his wife. They are out-of-state, but Sawyer would not disclose where they are.

Sanford offered a statement Friday about Sawyer's decision to leave.

"Joel has been a wonderfully devoted and skillful member of our team. The people of our state have benefited greatly from his service, as has this Administration, and I sincerely thank him," Sanford said. "We will miss him, but I join the rest of the staff in wishing Joel and his young family all the best in their future endeavors."