Supporters of Venezuela's President Hugo Chavez celebrated his anticipated victory in the presidential election in the capital Caracas as polls closed.
The incumbent is being challenged by 40-year-old state governor Henrique Capriles.
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Mladic, now 75, was the military commander of Bosnian Serb forces in the 1990s, who fought against the Bosnian Croat and Bosniak armies.
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His representatives said Cassidy, who was hospitalised last week, died "surrounded by those he loved."