OAKLAND (CBS SF) — The U.S. Coast Guard allowed the Rotterdam Express to depart from the Port of Oakland early Thursday after the cargo ship was cleared of any involvement in a massive oil spill fouling beaches in Southern California, a company spokesman said.

Nils Haupt, a spokesman for the German flagged Hapag Lloyd, emailed KPIX 5 that “we are no longer under investigation” and that the vessel was heading to Mexico.

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Coast Guard investigators boarded the massive cargo ship after it docked at the Port of Oakland Wednesday in an attempt to determine if its anchor may have snagged and bent the pipeline off Huntington Beach.

AP reviewed tracking data that appeared to show the Rotterdam Express made three unusual movements over two days that appeared to put it over the pipeline.

Both MarineTraffic and Hapag-Lloyd claim the GPS location data was erroneous.

Captain John Konrad, who publishes a website on the maritime and offshore industry said there are many unanswered questions as they look into whether or not the ship had anything to do with the oil spill.

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Workers clean contaminants from the Talbert Marsh on Wednesday, October 6, 2021, the fifth day after an oil spill off the coast of Huntington Beach threatens the ecosystem.(Photo by Mindy Schauer/MediaNews Group/Orange County Register via Getty Images)

“Did he have the right charts? Did the vessel traffic service advise him? Was this an old pipeline that maybe wasn’t properly charted? These are the questions we have to ask,” Konrad said.

The ruptured pipeline may have spilled nearly 150,000 gallons of crude oil into the ocean, according to the U.S. Coast Guard.

Federal transportation investigators say a backup of cargo ships at California ports may also have played a role in the spill, as ships have been forced to drop anchor off the coast because of overcrowding at ports and berths.

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Andrea Nakano contributed to this report.