After a full day of "Where in the world is Gov. Mark Sanford?" the governor's office said late Monday that the state's chief executive went hiking on the Appalachian Trail to clear his head.

The governor for months made regular appearances on national television news, and on Monday generated another round of headlines, this time for being missing in action since Thursday.

His wife said even she didn't know where he was.

The state's top law enforcement officer didn't know, either.

Sanford's staff said they knew, but it wasn't until after 10 p.m. Monday that they announced publicly that he'd gone for a hike.

Neither the staff, nor the first lady were worried about his safety or well-being, Sanford press secretary Joel Sawyer said.

"It isn't unusual for the governor to be out of pocket for several days after the legislative session," Sawyer said. "We knew he would be difficult to reach, and that he would be checking in infrequently."

Meanwhile, Lt. Gov. Andre Bauer left Charleston to drive to Columbia to be on standby should an emergency arise.

Bauer said that he called the governor's chief-of-staff to request an immediate phone call from Sanford.

"That request was denied because the governor's chief-of-staff does not know where the Governor is, and has not communicated with the Governor since he left South Carolina last Thursday," Bauer said in an e-mail statement that was sent within minutes of the late-night announcement from Sanford's office.

Bauer said his staff had been told earlier in the day by Sanford's staff that the governor's whereabouts were known.

"I cannot take lightly that his staff has not had communication with him for more than four days, and that no one, including his own family, knows his whereabouts," Bauer said. "I, along with the people of South Carolina, just want to know that our governor is safe."

Bauer is interested in running for governor when Sanford's second term expires in 2011. Term limits prohibit Sanford from running again.

The governor's disappearing act came two days after state lawmakers tossed out his vetoes and ended another bruising legislative session, much of which was devoted to the high-profile fight over $700 million in federal stimulus funds.

While that battle made him a rising star in some national Republican political circles, frustrated lawmakers at home took to calling him derisively "His Excellency" because they see him as rigid and uncompromising.

Reached at their beachfront home on Sullivan's Island in the afternoon, Sanford's wife, Jenny, said she didn't know where her husband was. She said he left Columbia on Thursday to work on a writing project.

"He's done this before, gone off to clear his head," she said, speaking quickly through the screen door. "He did miss Father's Day."

She expects him home probably sometime later this week. She said that on earlier occasions when he needed to clear his head he went to the family farm in Beaufort County, dismissing SLED security details in the process.

Earlier this month, Sanford was dealt one of the biggest blows in his effort to change the way government does business in South Carolina. The day the state Supreme Court handed down its decision to force Sanford to take the stimulus money, the governor said it was one of his biggest disappointments in public life.

Sawyer originally said Monday the governor's office wouldn't discuss the details of his travel arrangements or whether he dropped his security detail.

"The governor is taking some time away from the office this week to recharge after the stimulus battle and the legislative session and to work on a couple of projects that have fallen by the wayside," Sawyer said in a statement e-mailed to reporters.

Later in the day, Sawyer, amid a barrage of questions about where the governor is and who is in charge, provided more information.

Sawyer said, "Before leaving last week, he let staff know his whereabouts and that he'd be difficult to reach. Should any emergencies arise between the times in which he checks in, our staff would obviously be in contact with other state officials as the situation warrants before making any decisions."

Under state law, the staff can't make executive decisions without the governor's approval.

The Post and Courier has requested copies of cell phone records, e-mails and schedules for the governor during the past five days under the S.C. Freedom of Information Act.

Sen. Jake Knotts first alerted The Post and Courier to the situation Monday afternoon. Knotts said he called State Law Enforcement Division Director Reggie Lloyd on Saturday to confirm that Sanford had taken a SLED vehicle on Thursday and told his security to stand down.

"Ain't nobody seen from him or heard from him since," Knotts said. The West Columbia Republican, who spent 30 years in law enforcement, is very critical of the governor.