The two boys tore down the hall of Patton Middle School after lunch, swatting the bottoms of girls as they ran -- what some kids later said was a common form of greeting.

But bottom-slapping is against policy in McMinnville Public Schools. So a teacher's aide sent the gawky seventh-graders to the office, where the vice principal and a police officer stationed at the school soon interrogated them.

After hours of interviews with students the day of the February incident, the officer read the boys their Miranda rights and hauled them off in handcuffs to juvenile jail, where they spent the next five days.

Now, Cory Mashburn and Ryan Cornelison, both 13, face the prospect of 10 years in juvenile detention and a lifetime on the sex offender registry in a case that poses a fundamental question: When is horseplay a crime?

Bradley Berry, the McMinnville district attorney, said his office "aggressively" pursues sex crimes that involve children. "These cases are devastating to children," he said. "They are life-altering cases."

Last year, in a previously undisclosed prosecution, he charged two other Patton Middle School boys with felony sex abuse for repeatedly slapping the bottom of a female student. Both pleaded guilty to harassment, which is a misdemeanor. Berry declined to discuss his cases against Mashburn and Cornelison...

...The outlines of the case have been known. But confidential police reports and juvenile court records shed new light on the context of the boys' actions. The records show that other students, boys and girls, were slapping one another's bottoms. Two of the girls identified as victims have recanted, saying they felt pressured and gave false statements to interrogators...