Police found the gun in a vacant lot on the city's West Side Wednesday, one block away from where officers found the body of Jennifer Hudson's 7-year-old nephew, Julian King, inside a parked SUV.
The Chicago Tribune reports Jason Hudson owned an identical gun that he thought was stolen from the family's home a few months ago.
A public memorial for all three victims is scheduled for Sunday 4 p.m. at the Pleasant Gift Missionary Baptist Church.