On the morning of October 24, 2022, Central Visual and Performing Arts High School in St. Louis was the scene of a fatal school shooting. Jean Kirk Kuczka, a 61-year-old health and physical education teacher nearing retirement, was teaching on the third floor when a former student forced entry after shooting out a locked door. The gunman carried an AR-15-style rifle and hundreds of rounds of ammunition.

When the shooter reached Kuczka’s classroom she placed herself between him and her students and was shot and killed, an act described as shielding the children. A 15-year-old student, Alexzandria Bell, was also killed. Officers engaged the shooter on the third floor; he was struck by police gunfire, taken to a hospital, and later pronounced dead. No arrests were made. Investigators found a note in the suspect’s car and report that he had been blocked from buying a gun at a licensed dealer before obtaining the weapon in a private sale.

What details might help explain how the shooter gained access to the campus that morning?