Sanctuaries for big cats and other exotic, undomesticated animals such as monkeys have cropped up across the U.S. over the past few decades to take in animals whose owners could no longer handle them after they matured. Since 1990, according to one rescue organization, 20 people have been killed and more than 200 mauled by cats at zoos, sanctuaries and private homes. Even when strict safety protocols are established, human error can have tragic consequences. "It's a risky business when you're dealing with dangerous wild animals. You can't leave any room for error," said Vernon Weir of the American Sanctuary Association.