The necropsy on celebrity polar bear Knut, who died at the Berlin Zoo in 2011, was the most extensive ever conducted on an animal, zoologists say. The complete necropsy on the bear, who fell into the water in his enclosure and drowned after developing encephalitis, was released Friday, The Local.de reported Monday. The necropsy found swelling in the bear's brain caused by the disease was so severe, he would have died anyway if he hadn't fallen into the water. "An animal's death has never been so thoroughly investigated," said Claudia Szentiks, an animal pathologist with the Leibnitz Institute for Zoo and Wildlife Research, which conducted the necropsy. She said analysis of Knut's remains "reached brand new realms of research." Experts from the Free University in Berlin and the University of California were also involved in the post-mortem. The full report is published in the Journal of Comparative Pathology.