MEMPHIS, Tenn. -- A 17-year-old student charged with first-degree murder in the slaying of a Christian school principal told investigators he had planned to stab the woman on the third day of classes, when he knew he'd be alone with her in a classroom, police said Thursday.Eduardo Marmolejo was charged with killing 49-year-old Suzette York on Wednesday at Memphis Junior Academy, a Seventh-day Adventist school of about 100 students, Memphis police said Thursday.Read More... More on Crime