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A sailboat is tied to the Coast Guard dock at Horseshoe Cove on Monday, July 22, 2013, near Sausalito Calif. The boat's skipper was arrested yesterday when he allegedly fled after refusing to be boarded by authorities. (Frankie Frost/Marin Independent Journal) Frankie Frost

A Coast Guard encounter with an angry skipper off Sausalito triggered a chase out the Golden Gate Sunday that ended with the sailor facing an assault violation -- and authorities probing a "mysterious" saga.

John McCormick, who produced passports from both Ireland and New Zealand, was being held by authorities in San Francisco on suspicion of assaulting a federal officer.

The incident unfolded about 4 p.m. Sunday when officials said he threatened officers who wanted to board his 45-foot sailboat.

"He said he had weapons on board and he would use violence against us," said Mark Leahey, a Coast Guard spokesman in San Francisco.

A Coast Guard vessel on routine patrol spotted the sailboat anchored in Richardson Bay, and noted it lacked registration markings or other identification. The Coast Guard crew pulled alongside, but McCormick refused to allow them on board.

"He didn't let us on board, which makes us think he may be hiding something," Leahey said.

McCormick cut his mooring lines and headed out through the Golden Gate. The Coast Guard cutter Sockeye and a boarding team from Station Golden Gate gave chase, following the vessel to an area about two miles west of Ocean Beach.

When officials boarded the sailboat, a "minor altercation" broke out in which McCormick "lunged at an officer," Leahey said. No one was hurt.

An initial search of the vessel turned up nothing unusual, Leahey said, adding a more exhaustive examination of the vessel will be launched pending consultation with federal attorneys. The sailboat was towed back to Station Golden Gate.

Leahey said officials are comparing a recording of someone who made fake SOS calls on Sunday to determine if McCormick is the culprit.

"There's a lot of questions still to be answered," the Coast Guard official said. "Something mysterious is going on."

Contact Nels Johnson via email at ij.civiccenter@gmail.com. Follow him at twitter.com/nelsjohnsonnews