Suspect bought AR-15 style rifle used in skyscraper shooting from former co-worker

Incident Summary - A shooting occurred at 345 Park Avenue, resulting in four fatalities and the shooter's suicide [1] - The shooter, Shane Tamora, used an AR-15 style rifle in the attack [1] - Tamora had a documented history of mental illness [1] - Authorities found a second suicide note and several prescriptions, including anti-psychotic and anti-epileptic medications, in Tamora's Las Vegas apartment [3] - A suicide note found on Tamora's body indicated he believed he had CTE, a degenerative brain disease [3] Investigation Details - Tamora purchased the AR-15 style rifle from a former coworker for $1,400 [1] - The former coworker legally purchased the gun, but the legality of the sale to Tamora is under review [1] - Tamora also purchased a black BMW from the same coworker, which he used to drive to New York City [2] - Investigators are exploring Tamora's motive and whether others were involved [2] - Tamora received two phone calls during his cross-country drive, including from an unknown caller in New Jersey the day of the attack [5] Victims - Aland Etienne, a security officer, was among those killed [4] - Julia Heyman, 27, was another victim [4] Potential Target - Investigators believe Tamora may have been targeting NFL headquarters at the skyscraper [3]