The head of the New York Police Department said that investigators plan to question a man who supplied parts for a gun used in the attack on Monday.

Four victims, including an NYPD officer and a Blackstone executive, were killed in an NYC shooting at 345 Park Avenue.

Tamura worked as a surveillance department employee at the Horseshoe hotel and casino in Las Vegas, a spokesperson for the Horseshoe said on Tuesday. Several squad cars from the Las Vegas Metro Police were seen at the entrances to a gated neighborhood where Tamura was believed to have lived.

Tamura had apparently driven across the country from Nevada before killing four people in a shooting rampage in Manhattan.