"A publicity-addicted polar bear that became famous after his mother rejected him at birth died Saturday, a Berlin Zoo official said.

Knut, who was four years old, was alone when he passed away in his compound, bear keeper Heiner Kloes said.

The cause of death was unknown.

A necropsy is scheduled for Monday to figure out what killed the bear that was hand-raised by a team of zoo keepers since birth.

Knut was unable to care for himself after his mother rejected him following his 2006 birth, leaving humans to raise him.

He became a cause celebre when animal activists claimed it would be better for Knut to die than to be weaned by man..."

-- Aww... Remember this little guy? Super sad. =(

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