Police are retracing Tamura's movements from Nevada to New York after a Midtown Manhattan shooting that left four people dead and another wounded

Shane Tamura, the gunman who killed an NYPD officer and three civilians before taking his own life inside a Midtown Manhattan Park Avenue skyscraper, left a second suicide note behind in his Las Vegas home,

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