Tristyn Bailey was found dead on Sunday night in St. Augustine, Florida She had been stabbed a 'horrific' number of times, Sheriff Robert Hardwick revealed on Tuesday Aiden Fucci, 14, has been charged with her murder and is in juvenile custody Prosecutors have not decided yet whether to charge Fucci as a child or adult Before police found Tristyn's body, Aiden posted a selfie on Snapchat with the caption 'hey has anybody seen Tristyn?' Cops say the 'egregious' selfie shows he was 'proud' of what he'd done The motive for the crime still has not been established; the pair were classmates