A California marine biologist is facing up to 20 years in prison and half a million dollars in fines for allegedly feeding a group of killer whales and then altering footage of the incident and lying to authorities.

In addition to her carrying out maritime research, Nancy Black operates the popular Monterey Bay Whale Watch tours and has been featured on PBS, National Geographic and Animal Planet. But on Wednesday, Black was charged with four violations of the Marine Mammal Protection Act. Black's attorneys say she was only doing scientific research.

If she's convicted, Black could face up to 20 years in prison and half a million dollars in fines. She could also be fined up to $100,000 for each whale feeding charge, which also carries a year in prison sentencing term.

Black is accused of feeding killer whales during a 2005 research trip, which was investigated by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Department of Justice. She had previously worked with federal agencies to help study whales, including the National Marine Mammal Laboratory, which is part of NOAA.

Black was asked to provide video of the October 2005 trip, and authorities say they believe she edited the video illegally. "She was out whale-watching with a full complement of passengers and spotted a humpback whale. It was a friendly whale, which loves to come up close to a boat and breach and frolic," said Black's attorney Lawrence Biegel. "There's video of this, which she turned over, of this whale doing exactly that, literally going from one side of the boat to another."

Biegel says the killer whales were feeding off of gray whale blubber already in the ocean and that Black did not feed them.

"In the specific incident in question, Ms. Black used an underwater camera and filmed the eating habits of killer whales who were feeding off free floating pieces of blubber from a gray whale that had been killed by a pack of killer whales," Biegel said.

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"She was never hiding what she did or how she did it. In fact, she was acting with the knowledge of other marine mammal scientists, some of whom work for agencies of the federal government," he said. Biegel said Black had a permit granted by the federal government to conduct the research.

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