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.

Shane Tamura was identified as the Manhattan active shooter suspect. That's according to the New York Post, which cited law enforcement sources. Authorities have not yet formally named the gunman, who was pictured in a widely published photo toting a rifle and calmly walking down the sidewalk