After minutes of frenzied work to save Dawn Brancheau, 40, the whale was finally corralled, but still refused to unclench its teeth and let go of her body, according to investigative reports released by Florida's Orange County Sheriff's Office.
Investigators said Ms Brancheau died from multiple traumatic injuries and drowning.
"The whale would not let us have her," another trainer, Jodie Ann Tintle, told investigators after the attack on Wednesday.
In the investigative reports, Ms Brancheau's co-workers described the swiftness of the attack and the furious response that came after alarms sounded around the pool. Employees who were at other pools, behind computers or emptying coolers of fish rushed to the scene.
The reports include the first extensive accounts from employees who witnessed the attacks at the park in Orlando.
Jan Topoleski, who monitors trainers' safety during shows, said he saw Ms Brancheau lying on the deck face-to-face with the 22ft-long, 12,000lb whale and communicating with him just before the attack. He said the whale, named Tilikum, bit Ms Brancheau's hair and pulled her into the pool within about two seconds. Mr Topoleski sounded an alarm and grabbed safety equipment.
It was not clear how long it took workers to finally trap the whale in a pool with the lift, which they used to remove it from the water. One witness said it seemed like 10 minutes, but another said it could have been as long as 30 minutes.
Numerous employees said the whale's jaw had to be pried open to remove Ms Brancheau. But her hand remained in the clench of Tilikum and they had to pry the whales's mouth open again.
When they finally got Ms Brancheau free, her body was placed on the deck and her wetsuit cut off. Paramedics pronounced her dead, and her body was covered.
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