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Debate raged Thursday over what to do with Tilikum, the five-tonne killer whale that dragged its veteran trainer into a tank and killed her before horrified onlookers in Florida.
Police and the Sea World marine park have launched investigations to determine exactly what transpired but their appears to be no doubt Tilikum became visibly agitated and then killed his 40-year-old female trainer.
Witnesses said the whale, linked to two previous deaths since 1991, leapt out of its tank to grab Dawn Brancheau during a noontime show on Wednesday before dragging her into the water to her death.
Victoria Biniak, who witnessed the horror show unfold, said the black-and-white bull orca, the largest killer while in captivity, shook Brancheau violently before she died.
Tilikum was "kind of going out of the water and grabbing a human and was shaking her violently. The way that he was thrashing around, and a shoe actually fell off and the sirens immediately went off and people started running everywhere," she told NBC.
SeaWorld has so far not indicated whether the incident was captured by its extensive camera system or by one of the visiting tourists -- footage that would play a key role in the investigation.
Brancheau "may have somehow been pulled into the water by the whale rather than slipping or falling. Witnesses are saying the whale may have actually grabbed her," Jim Solomons of the Orange County Sheriff's office told AFP.
Solomons said an autopsy of Brancheau's body was due to be completed later Thursday, as the medical examiner seeks to rule on a preliminary cause of death.
"We must emphasize that this is an extraordinarily difficult time for the SeaWorld parks, and our team members," the park said in a statement.
"We have never, in the 46-year history of SeaWorld, experienced an incident like this, and all of our procedures will come under review as part of the investigation."
Rights groups meanwhile condemned the use of animals in theme parks with People for the Ethical Treatment of Animals (PETA) saying the death was a "tragedy that didn't have to happen."
PETA urged SeaWorld to leave marine mammals in the ocean rather than confining them to an area "the size of a bathtub" for them, and suggested that switching to giant robotics would be a "win-win" situation.
SeaWorld did not indicate what the future may hold for Tilikum, a big breeder worth millions of dollars, but activists pressed for a controlled release.
Naomi Rose, a marine mammal scientist with The Humane Society, suggested he be released in an open ocean sea-pen the size of a football field.
"He could be trained to adjust to going out into the open ocean to exercise and get more choices and then maybe his stress would be reduced," she said, suggesting Tilikum may have simply been trying to play with his trainer.
"If they keep him in isolation the way they do, they keep him in that small tank that he's in, this is going to happen again."
A full release might be complicated for Tilikum, who has been captive for nearly 27 years.
Tilikum, whose name means "friend" in the Chinook Jargon language spoken among native Americans in the Pacific Northwest, is among the killer whales, dolphins and seals whose shows have made SeaWorld popular.
But the whale known simply as "Tilly" has been linked to two previous human deaths: in 1991, when a part-time trainer at the Sealand of the Pacific facility in Canada was killed in his tank, and in 1999, when a man died after sneaking into SeaWorld after closing to swim with the mammals.
