COLVILLE, Wash. (AP) — A judge has granted a defense request for more time to complete a second mental exam for two fifth-grade Colville boys accused of bringing weapons to school in a plot to kill a classmate. The boys, ages 10 and 11, entered a courtroom in shackles Wednesday at the scheduled start of a hearing to determine whether they can be prosecuted in juvenile court. Stevens County Prosecutor Tim Rasmussen says Washington's criminal justice system presumes that children younger than 12 do not have the capacity to understand they are planning to commit crimes. A judge can allow prosecutors to pursue charges if they can show the youths understood the difference between right and wrong. The boys were arrested Feb. 7 at Fort Colville Elementary School after a fourth-grader saw one playing with a knife on a school bus and told a school employee. A backpack search also turned up a .45-caliber semi-automatic pistol and ammunition. Police say the boys described how they planned to kill a girl and possibly harm a half dozen other students. The capacity hearing has been rescheduled for March 15.