New York City police detectives searched a studio apartment in Las Vegas that belonged to the suspected gunman in Monday's mass shooting at a Midtown Manhattan.

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.

A man who killed four people at a Manhattan office building bought the rifle he used in the attack, and the car he drove across country, from his supervisor at a Las Vegas casino, authorities said Wednesday.