Thomas Dorflein, 44, Berlin, was found dead in his apartment under what the British newspaper The Independent said were suspicious circumstances.

Dorflein had been ill recently and police would not comment on the possibility of suicide, according to the newspaper.

Dorflein was a key figure in the saga of Knut, the tiny cub who was rejected by its mother and would have died a short time later had it not been raised by humans at the Berlin Zoo.

Dorflein doted on Knut, feeding it and even playing Elvis Presley songs on a guitar to calm the cub.

Knut became a celebrity and some 500 journalists chronicled its first public appearance in 2006.

The Independent said Dorflein was taken off Knut duty last year due to concerns the bear would become too bonded to its human caretaker