On a chilly Tuesday morning in November 2007, 16-year-old Alex Davis was taking a shower before school when his mother, Betty, knocked on the bathroom door. There was someone downstairs, she said, a New York state trooper who had come at 7 a.m. to the family’s farm outside Rochester.

“She said, ‘I think it’s about Laurie,’ ” Alex recalls. “My stomach kind of dropped, and I thought, ‘This is not going to be good.’ ”

The previous Friday, after coming home from football practice with a few teammates, Alex had exchanged text messages with Laurie, a 14-year-old freshman (whose name has been changed in this story, as has Alex’s and his family’s). While his friends played Guitar Hero on his PS2, Alex, captain of the football, basketball, and tennis teams, read a message from Laurie saying she wanted to be a cheerleader.