Berlin zoo director Bernhard Blaszkiewitz poses next to a sculpture of the scull of polar bear Knut during a news conference in Berlin, April 1, 2011. Celebrity polar bear Knut died by drowning the Berlin Zoo said on Friday. Knut, who won global fame as a cute cub, died suddenly in front of hundreds of horrified visitors on March 19 aged four after he fell unconscious into a pool at his enclosure. The polar bear suffered from viral encephalitis, an inflammation of the brain, which caused him to collapse before he drowned, a necropsy indicated. REUTERS/Tobias Schwarz (GERMANY - Tags: ANIMALS SCI TECH)