Police Confirm Gun Used in Hudson Murders
(Video)

Hudson's family, meanwhile, plans to hold a public memorial service Sunday at the Pleasant Gift Memorial Baptist Church, located at 4526 South Greenwood Avenue for her mother, brother and nephew. The service will be open to the public from 4 to 7 p.m.

Neither the actress nor her sister, Julia, will attend, though other relatives will be present.

The .45-caliber Sig-Sauer semiautomatic pistol was recovered in the bushes of a vacant lot on the West Side a block away from the site where the nephew's body was found Monday morning. Police immediately had suspected it was the gun used in the killings because the unfired bullets matched the make and model of shell casings found at the murder scene, sources said.

The investigation continues as police try to tie their evidence to a suspect. William Balfour, the estranged husband of Hudson's sister Julia, remains in custody after being questioned in the case, but he has not been charged in the murders.

The U.S. Bureau of Alcohol, Tobacco, Firearms & Explosives had also earlier traced the recovered gun to an original owner in Michigan, who reported it stolen, sources said. Investigators are trying to retrace the weapon's path to Chicago.