William Scott Ritter Jr., a former United Nations weapons inspector who gained renown for his criticism of U.S. foreign policy in the Middle East, contends his online sexual encounters with teenage girls were only fantasy. Nearly two years ago, Ritter, of Delmar, watched his computer screen reveal that an anonymous person who had been exchanging sexually charged messages with him for 80 minutes was not a 15-year-old girl. It was a cop from a small town in northeast Pennsylvania, alone in his station house and trolling the Internet for suspected child predators. Ryan Venneman, a detective for the Barrett Township...