Tamura's supervisor at the Horseshoe Las Vegas legally bought the AR-15-style rifle he sold to Tamura for $1,400, the New York Police Department said Wednesday.

The gunman who opened fire at a Manhattan office building Monday, killing four people before taking his own life, legally purchased the rifle used in the attack, according to an attorney for the Las Vegas casino supervisor he bought it from.

New York City investigators believe a co-worker of the Las Vegas man who killed four, including a police officer, provided a component of the deadly weapon, the 8 News Now Investigators have learned.