India, July 29 -- Shane Tamura killed four people Monday night when he opened fire at 345 Park Avenue, a corporate skyscraper that houses the NFL's and investment firm Blackstone's headquarters.

According to authorities, the 27-year-old shooter from Las Vegas had a history of mental health problems. He played football in high school, but according to acquaintances, there was no sign that he had any plans to play in the NFL.

CNN reports that Tamura's purported suicide note was discovered from his back pocket at the crime scene in New York City. According to reports, it said: "Terry Long football gave me CTE, and it caused me to drink a gallon of antifreeze. You can't go against the NFL; they'll squash you."

"Study my brain, please. I'm ...