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 gunman who shot and killed four people at a midtown Manhattan building Monday before killing himself bought the murder weapon for $1,400 from his boss at the Las Vegas casino where he worked security, NYPD officials said Wednesday.

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.