“Authorities on Wednesday identified the murder weapon as a Smith & Wesson M&P 15 semi-automatic rifle and said Crimo bought it in 2020”
https://nypost.com/2022/07/06/highland-park-suspect-robert-crimo-bought-rifle-online-report/
The article said the Crimo owned five guns.
From FFL dealer Bud’s Guns to another FFL dealer.