Mirko FilipoviÄ ( born September 10 , 1974 in Zagreb , Croatia ) is a Croatian mixed martial artist that currently fights for the UFC known by his nickname Mirko Cro Cop which he gained when he was in the LuÄ ko Anti-Terrorist Unit . Mirko FilipoviÄ ( ; born September 10 , 1974 ) is a Croatian heavyweight kickboxer , mixed martial artist , and former law enforcement officer .