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 police detectives searched the Las Vegas studio apartment of the suspected gunman in Monday's mass shooting at a Midtown Manhattan office tower and found what law enforcement sources described to ABC News as a suicide note he left for his parents.

Detectives searched the studio apartment of 27-year-old Shane Tamura, who shot five people on Monday before killing himself, in Las Vegas and found 100 9mm rounds, a tripod for the rifle used in the shooting, and an empty hand box for a revolver, police said Wednesday, according to The Hill.