Jennifer Hudson's mother, brother and 7-year-old nephew were shot to death. The boy's stepfather is a person of interest in the case, but has not been charged.
Police found a .45-caliber Sig-Sauer semiautomatic pistol in a West Side vacant lot a block away from where the child's body was discovered in a parked SUV Monday morning, three days after the bodies of his grandmother and uncle were discovered in their South Side home.
The Tribune said police immediately suspected the gun was the weapon used in the slayings because the unfired bullets matched the make and model of shell casings found at the house.
Sources said investigators determined the firearm was reported stolen by its original owner and they are now trying to figure out how it ended up in the hands of the killer.
Hudson's family said it will hold a public memorial service Sunday for the three victims, however, neither the 27-year-old Academy Award winning singer-actress or her sister, Julia, are to attend, the newspaper said.
A private memorial service has been scheduled for Monday.
Hudson won an Oscar for her role in the movie musical "Dreamgirls." She also co-starred in the "Sex and the City" movie and can be seen in the current release "The Secret Life of Bees."