"Every time that arm went back and every time that arm went down, that was premeditation," Larizza said.
Investigators said that Fucci had also told several friends that he planned to kill someone, though it wasn't clear whether Bailey was his intended target from the beginning, Larizza said.
Bailey was last seen early May 9 at the community center in the Durbin Crossing community south of Jacksonville. Bailey and Fucci attended nearby Patriot Oaks Academy, where Bailey was a cheerleader.
Bailey's parents reported her missing later that morning, and a neighbor found her body in a heavily wooded area that evening, the St. Johns County Sheriff Office said. Fucci was arrested the next day on a second-degree murder charge.