He is the mystery man of the nation's worst oil spill, the third mate who was on watch when the Exxon Valdez ran aground and dumped more than 10 million gallons of crude in Prince William Sound.

Little has been seen of Gregory Cousins since the March 24 accident, and federal officials don't expect him to surface until the May 16-19 hearings in Anchorage to assess what happened and how to prevent a recurrence.Capt. Joseph Hazelwood, who the Coast Guard says was the only person aboard authorized to navigate the tanker through the sound, blamed his third mate when the Coast Guard radioed his ship an hour after the wreck.

"Joe Hazelwood here," the skipper answered when Coast Guard Cmdr. Steve McCall in Valdez asked for a damage report.

"A little problem here with the third mate, but we're working our way off the reef," said Hazelwood, who tried to rock the ship free before shutting down the engines and waiting for help.

Cousins had signed on with Exxon as a third mate, although he had obtained his second mate's certification Jan. 12.

"That's not unusual," said Coast Guard Lt. Cmdr. Gary Kaminski in Washington, D.C. "With fewer positions available, people set sail at positions lower than their license."

A second mate is the navigator and is in charge of maps and charts. The third mate is in charge of maintenance and the inventory of firefighting equipment. They and the chief mate, in charge of cargo, alternate four-hour watches on the bridge.

Hazelwood turned the 987-foot tanker and its 42 million gallons of oil destined for Long Beach, Calif., over to Cousins sometime after a state pilot with federal pilot authority left the ship at Rocky Point.

Bligh Reef was seven miles away.

"At that time the master (Hazelwood) was in the wheelhouse," said Coast Guard Cmdr. Darryle Waldron. "The master had federal pilotage (authority) for Prince William Sound through the entrance. The mates didn't have the necessary endorsements on their licenses."

The pilots used to navigate ships out of the sound to the Gulf of Alaska until the 1980s when a smaller ship taking a pilot back to Valdez capsized in rough seas. The pilot nearly died, and the rules were eased.