Here in New York, police have revealed new details about Monday’s mass shooting in Midtown Manhattan. Investigators say 27-year-old gunman Shane Devon Tamura used an M4 assault-style rifle in the attack, which killed a police officer, a security guard, a real estate associate and a senior executive at the investment firm Blackstone. However, the shooter appeared to be targeting the NFL’s corporate headquarters. In a three-page handwritten suicide note, Tamara wrote that playing football had left him with the neurodegenerative disease CTE, which is linked to head trauma. His note read in part, “Please study brain for CTE. I’m sorry. The league knowingly concealed the dangers to our brains to maximize profits. They failed us.”