here, and read more about Doerflein here. See more images from Knut's life here.
According to Spiegel Online, Knut suddenly collapsed and died in the water area of the polar bear enclosure as 600-700 visitors to the zoo watched. Knut was hand-raised by zookeepers after his mother rejected him at birth, and the keeper pictured with him, Thomas Doerflein, passed away of a heart attack in 2008 at the age of 44. Read the full Spiegel story