A fifth shooting victim -- an NFL employee, according to Commissioner Roger Goodell -- was injured and taken to the hospital in critical condition, officials said. That victim was listed in stable condition on Tuesday morning, according to a source familiar with the individual's status.

The gunman who killed four people at an office building in New York City on Monday evening left his home in Las Vegas, Nevada late last week.

Study my brain please,” read a note left by the gunman accused of killing four people in a building that houses NFL’s headquarters