LAS VEGAS (KSNV) — A person from Las Vegas bought a piece of the rifle used by Shane Tamura in the deadly shooting at a New York office building this week, according to multiple reports.

A supervisor at Horseshoe Las Vegas allegedly supplied the lower receiver for Tamura's AR-15, the New York Post first reported Tuesday.

NBC News later reported that detectives spoke with an "associate" who supplied the lower receiver of the gun, citing two officials familiar with the investigation.

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The lower receiver includes the magazine well and pistol grip, and it's the only part of an AR-15 classified as a firearm under federal law, the New York Post said.

Horseshoe confirmed Tamura worked at the resort as a surveillance department employee.

Investigators also found ammunition, antidepressant medication and a note pad in Tamura's Las Vegas home, per NBC News. There was a handwritten message from Tamura to his family with a brief apology.

Authorities say Tamura, 27, shot and killed four people - NYPD Officer Didarul Islam, Aland Etienne, Julia Hyman and Wesley Lepatner - before he took his own life.

New York Mayor Eric Adams said they believe he was targetting the NFL's headquarters, and an NFL employee was seriously wounded in the attack.