Nikolas Cruz—the 19-year-old who allegedly killed 17 students at a Parkland, Florida, high school on Feb. 14—researched the 1999 Columbine massacre that left 13 victims dead as he planned the attack, the Miami Herald reported. The detail was revealed Tuesday by a state commission created in the wake of the shooting at Marjory Stoneman Douglas High School. The 20-member group, which includes three victims’ parents and local law enforcement, also announced that some teachers were forced to lock their doors from the outside and that police radios were jammed on the day of the shooting, creating even more chaos and confusion. The commission plans to release a full report in January after reviewing school-safety measures and thousands of documents related to the shooting. During the commission's Tuesday meeting, Andrew Pollack, whose daughter was killed during the tragedy, could only call Cruz by his prison number, 18-19-58.