LAS VEGAS (KSNV) — New details have emerged in the investigation of the deadly New York shooting involving Shane Tamura, a former employee at the Horseshoe Casino.

Tamura, who worked in the surveillance department at Horseshoe Casino, did not report for his shift on Sunday.

Authorities reported that Tamura's supervisor sold him part of the gun used in the shooting. His supervisor at Horseshoe Casino is Rick Ackley.

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Ackley's attorney, Chris Rasmussen, provided us with this statement:

"Rick Ackley administered the transfer of the firearm used in the tragedy in New York lawfully, complying with Nevada and federal gun laws."

When asked about charges, Rasmussen said Ackley is not a suspect and will not face any charges.

Investigators have revealed that Tamura left notes attributing his motive for the shooting to chronic traumatic encephalopathy (CTE). During a search of Tamura's Las Vegas apartment, officials found psychiatric medication, a single rifle round, a suicide note, anti-epileptic and anti-inflammatory medications, a tripod, a box for the revolver found in Tamura’s car in New York, and about 100 9mm rounds for the gun.

Authorities discovered that Tamura purchased part of the gun from Ackley for $1,400.

The investigation continues as new information surfaces daily about the victims, the situation, and Tamura's actions.