WASHINGTON -- The CEO of Wackenhut Corp., which recently lost its job protecting 10 nuclear power plants after guards at one plant were caught napping, has left the company.

The Palm Beach Gardens, Fla.-based security provider, a subsidiary of British based security giant G4S PLC, thanked Gary A. Sanders for his service, but did not say why he left in a news release issued today. Grahame Gibson, a board member and G4S's chief operating officer, now has responsibility for the company's North American operations.

After guards at one plant were found to be sleeping on the job last year, Chicago-based utility Exelon Corp. last month said that by July it would replace Wackenhut with an in-house security force at its 10 nuclear power plants.

Wackenhut officials have said the apparent lapses in attentiveness at the Peach Bottom plant in Pennsylvania were "an anomaly." Exelon said it took action even though a review of security at its other plants found "no significant deficiencies."

Since a videotape arose that showed guards at the Peach Bottom plant nodding off, the U.S. Nuclear Regulatory Commission last month asked commercial nuclear power plant operators to provide new information about their security practices. The agency in October confirmed guards had been sleeping on the job at the plant.

Wackenhut also provides security, fire and other services to Department of Defense locations in Iraq.

Shares of G4S fell about 1.4 percent to $425.32 on the London Stock Exchange in afternoon trading.

First Published: January 10, 2008, 5:15 p.m.