Police have identified the man who they say entered a Midtown Manhattan office building wearing body armor and opened fire, killing four people with a high-powered rifle, as Shane Devon Tamura.

Shane Tamura — who fatally shot four people at a Midtown East office building — said in a suicide note he believed he suffered from CTE and requested his brain be studied.

The gunman, who said in a note he believed he had CTE, targeted skyscraper that houses the NFL's headquarters.