More than a decade before he turned a Midtown NYC office building into a killing ground, Shane Tamura stood out as a rising star on a high school gridiron. Police believe the 27-year-old shooter’s obsession with CTE,

In the photos first shared online, Tamura was captured walking into 345 Park Avenue with an assault rifle in his hand while decked out in a suit.

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