1/83/8 FORT MILL | Per and Cheryl Henriksen's sons sat on a couch eating snacks and watching TV. They were home alone when a red car pulled in their driveway and a stranger broke in. The intruder had been to their home minutes earlier and rang the doorbell six times, but the boys - ages 12 and 8 - knew not to answer. Instead, the oldest boy called his father and the younger one went to the garage. ...