The New York City Police Department sent detectives to Las Vegas to work with the Bureau of Alcohol, Tobacco and Firearms to execute search warrants and continue the investigation into Monday's deadly shooting inside a Midtown Manhattan office building.

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.

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.