The gunman who opened fire at a Manhattan office building Monday, killing four people before taking his own life, legally ...

The attorney for the man who sold what would become the deadly weapon in a mass shooting in New York City earlier this week said his client legally sold his co-worker the gun.

Authorities probe the weapon origins in the Manhattan shooting by Shane Tamura, who bought a rifle from his supervisor.

A long-time office cleaner said she encountered the suspected in a mass shooting in a Midtown Manhattan office building.