The New York City Office of Chief Medical Examiner says an examination of Shane Tamura determined that the Midtown mass shooter had low-stage chronic traumatic Encephalopathy, also known as CTE.

Tamura died by suicide after he opened fire at the NFL headquarters on Park Avenue in Manhattan. The OCME says that CTE may be found in the brains of people after they died who had a history of repeated head trauma.

Investigators previously said that a note was found in the former high school football player's pocket that claimed he had CTE. Four people died during Tamura's July attack, including an off-duty NYPD officer working as a security guard.