The gunman who killed four people at a Manhattan office building in July was affected by Chronic Traumatic Encephalopathy, or CTE, medical officials say.

"Following a thorough assessment and extensive analysis by our neuropathology experts, OCME has found unambiguous diagnostic evidence of Chronic Traumatic Encephalopathy, also known as CTE, in the brain tissue of the decedent," the state's medical examiner wrote on Friday. "The findings correspond with the classification of low-stage CTE, according to current consensus criteria."

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The gunman killed four people, including a New York City police officer. Authorities reported the he was targeting the NFL.

The suspect, identified as Shane Tamura

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