The FBI served search warrants at the business and home of the co-owner of a paparazzi agency, trying to determine whether someone attempted to hack into the computer system at US Weekly, according to several law enforcement sources and the co-owner's spokesman. Federal agents want to know whether one of the owners of Sunset Photo and News attempted to learn what stories the staff at US Weekly, a Hollywood gossip magazine, was working on, said the sources, who spoke on the condition of anonymity.