SAN FRANCISCO &

Federal investigators began a criminal investigation into San Francisco Bay's worst oil spill in nearly two decades by questioning crew members of a container ship that struck the Bay Bridge, ripping a gash in its fuel tank.




Crew members of the Cosco Busan will be allowed to leave after federal investigators complete interviews that started Sunday, said Capt. William Uberti, the U.S. Coast Guard commander for the bay region.




Uberti said he notified the U.S. attorney's office Saturday about problems involving management and communication between the officers on the ship's bridge at the time of the crash. He declined to elaborate, except to say: "It was just the way that everybody interacted" on the bridge.




The bridge personnel included the helmsman, watch officer, and ship's master &

part of the Cosco Busan's Asia-based crew &

as well as the pilot, Capt. John Cota, among the most experienced of the seamen who guide ships through the bay's treacherous waters.




Darrell Wilson, a representative for Regal Stone Ltd., the Hong Kong-based company that owns the Cosco Busan, declined to comment Sunday on the investigation.




A call to the U.S. attorney's office for Northern California was not returned Sunday.




The ship struck the bridge early Wednesday, causing no structural damage to the span but leaking some 58,000 gallons of fuel oil into the bay. The thick, toxic fuel has fouled miles of coastline, forced the closure of nearly two dozen beaches and piers and killed dozens of seabirds.




Meanwhile, the head of the Coast Guard defended his agency's response to the spill while pledging a full and transparent investigation.




"On the surface it would appear that we did everything by the book in this case as far as responding," Commandant Adm. Thad Allen told The Associated Press while en route from Washington, D.C., to San Francisco to survey the damage.




"However, having done this work for over 36 years, nothing is as it seems at the start," he said. "We need to recover all the information, make sure all the facts are established."




The Coast Guard has been criticized for a lag time of several hours between when agency officials learned that the spill was 58,000 gallons &

not 140 as initially reported &

and when that information was given to local officials and the public.




Allen said it may have taken time to figure out the extent of the spill partly because gear used to measure how much fuel is in the oil tank were damaged in the crash. He also noted the poor visibility at the time &

a quarter-mile to an eighth-mile in the fog.




"You don't turn 900-foot vessels on a dime," he said, "and given the visibility at the time I think it would be difficult to assess whether or not the bridge itself was visible."




U.S. Sen. Dianne Feinstein, D-Calif., met with Coast Guard officials Sunday and called for improvements to the system for responding to spills. She said communication needs to be better between the Coast Guard and the communities where toxic sludge began washing up shortly after the crash.




"There were a lot of unusual things such as weather, but that should not excuse this," Feinstein said.




After touching down in San Francisco, Allen boarded a Coast Guard helicopter for a one-hour aerial tour of affected areas of the bay with Coast Guard Adm. Craig Bone, the agency's top officer in California.




The helicopter swooped over the Golden Gate Bridge and hovered near the Bay Bridge, where the wooden bulkhead surrounding the bridge support was splintered and broken where the ship had struck it. Shiny slicks of oil still floated on some parts of the bay, while crews in hazmat suits trudged along beaches near Sausalito and Emeryville as couples walked nearby and people flew kites.




More than 10,000 gallons of oil had been recovered by Sunday, but much of the oil never will be, the Coast Guard said. Some will evaporate or dissipate and be absorbed into the ecosystem.




The National Transportation Safety Board, an independent federal agency that investigates major transportation accidents, arrived Sunday to start its own investigation. That inquiry, which will include an examination of the Coast Guard's response, could take up to a year, said Debbie Hersman, an NTSB spokeswoman.




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Associated Press writer Jason Dearen contributed to this report from San Francisco.