The Las Vegas Sun reports Backstreet Boys star AJ McLean chased down and helped catch a would-be thief who had dashed out of the Hard Rock Hotel’s jewelry store with a $40,000 diamond-encrusted ring. “The girl at the counter screamed that she could not leave the store, so A.J. just shot out of there like a rocket,” Vegas club personality Marklen Kennedy, a friend of McLean’s, revealed. McLean caught up to the man in the parking out, where he and a hotel security guard on a bicycle nabbed him. AJ was in town for this week’s Adult Entertainment Expo convention.