ROCK POINT, Md. (AP) _ Former CIA Director William Colby was missing and presumed drowned Monday after what the sheriff said was an apparent boating accident near Colby's vacation home.

Colby's canoe was found on a sandbar Sunday a quarter-mile from his home on the Wicomico River, and divers searched the rough and murky water for the 76-year-old former spy master.

``Right now, we are viewing it as an accident,'' Sheriff Fred Davis said. ``We're not ruling out foul play, but we never rule out foul play.''

Colby, who headed the CIA from 1973 to 1976 under Presidents Nixon and Ford, apparently went canoeing late Saturday, but his absence wasn't noticed until Sunday night, when neighbors became suspicious because his car was still in the driveway. Colby usually has returned to Washington by then.

Neighbors also said Colby did not raise his flag on Sunday as he had every other day.

A neighbor who checked his home found his radio and computer still on. Investigators found dinner dishes on a table and clam shells in the kitchen sink.

Davis said Colby's wife, Sally Shelton-Colby, was out of town but had spoken to him during the weekend. He told her he didn't feel well but was going canoeing anyway.

Neighbors said the water was rough Saturday and not good for canoeing.

``I don't see why a man his age would be out there,'' said neighbor Joseph Hervey. ``If I went out there it would be in a 16- to 20-foot boat _ not canoe.''

The sheriff ruled out the possibility of suicide.

Coast Guard crews searched the river for more than five hours late Sunday and resumed the search Monday morning. Authorities didn't know if Colby was wearing a life-preserver.

Colby is the second high-level CIA official to disappear in Maryland waters.

In September 1978, a 31-foot sloop belonging to John A. Paisley, who had retired four years before as deputy director of the CIA's Office of Strategic Research, was found unoccupied near Point Lookout, where the Potomac River and Chesapeake Bay meet. The area is about 15 miles from where Colby was canoeing.

Paisley's decomposed body was found in the bay a week later, weighted down by two diving belts and containing a gunshot wound to the head. Authorities said it wasn't clear if he was murdered or committed suicide.

Colby, who began his intelligence career parachuting into France to fight the Nazis, later headed the CIA's Saigon office during the Vietnam War.

In Vietnam, he was associated with Operation Phoenix, an infiltration effort to root out rural support for communist guerrillas. It led to sweeping arrests, torture and execution of suspects. Critics said most of those killed were innocent peasants.

He was dismissed by Ford as CIA director because of a growing feeling in the White House that he was cooperating too freely with congressional investigators looking into allegations of wrongdoing within the agency. The agency had been accused of plotting assassinations overseas and of spying on civilians in the United States.

Colby was born in St. Paul, Minn. He dropped out of Columbia University Law School to join the Army after his first year. He went into intelligence when he answered a call for French-speaking volunteers and joined the Office of Strategic Services, the CIA's forerunner.

Colby joined the CIA in 1950. After retiring from the CIA, he practiced law and was a consultant. A director of a U.S.-based investment fund called the Vietnam Frontier Fund, Colby was denied a visa to visit Vietnam in 1994.

Recently, Colby and former KGB Gen. Oleg Kalugin played themselves in a new interactive CD-ROM game, ``Spycraft: The Great Game.''

``We've got lots of former enemies,'' Colby said in an interview to promote the game. ``We fought a lot of them, and now we are allies. ... We have many kinds of games used in the government for training and to stretch the minds a bit.''