In a note left in his wallet, the shooter, referenced chronic traumatic encephalopathy, commonly called by its initials CTE, and criticized the NFL for covering up the traumatic brain effects of playing football.

Shane Devon Tamura — the man who killed at least four people in a New York City office building — claimed in a suicide noted that he suffered from chronic traumatic encephalopathy (CTE) while slamming the NFL. “Study my brain please,” Tamura, a former high-school football player, wrote in the note. "I'm sorry."