Shane Tamura, the Park Ave. gunman who killed an NYPD officer and three others before taking his own life, left behind a suicide note saying he suffered from CTE, a brain injury often linked to playing football, and was targeting the NFL — but took the wrong elevator, officials said Tuesday.

The gunman in the Manhattan office shooting has been tentatively identified as a 27-year-old Shane Tamura from Las Vegas, as per reports. He is believed to have died from a self-inflicted gunshot wound.