Diamond, Mo. (AP) -- No one will ever confuse Jim Murray with a teenager. His tall frame, broad shoulders and clipped gray hair give him away for the grandfather he is. But the 69-year-old retired police chief of this small Missouri town cuts a credible figure as a 13-year-old girl surfing the Web, looking for friends. He knows all the instant-messaging shorthand, the emoticons. Murray's retirement job from a rural home office has netted 20 arrests since he started in 2002. His latest catch was the biggest: four felony enticement charges against a town mayor, who after his arrest called...