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,

Tamura had apparently driven across the country from Nevada before killing four people in a shooting rampage in Manhattan.

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