Prosecutors argued Gray calculated his actions, choosing Sept. 4 for the Apalachee High School shooting as a surprise for Cruz's birthday. A forensic psychologist testified that Apalachee High School shooter Colt Gray can improve with treatment, while prosecutors argued the 16-year-old calculated the attack and exaggerated his mental illness. Apalachee High School shooting testimonyWhat we know:Defense and prosecution attorneys agreed during court testimony that 16-year-old Colt Gray grew up in a troubled home. Court testimony revealed Gray was obsessed with Parkland, Florida, high school killer Nikolas Cruz, even discussing sexual acts involving Cruz in online chats. An investigator with the district attorney's office stated Gray's Discord chats revealed he chose Sept. 4 for the school shooting as a surprise for Cruz's birthday.