Arrangements for a memorial service in Chicago in honor of the murdered mother, brother and nephew of Academy Award-winning actress Jennifer Hudson were in progress on Sunday, as the Pleasant Gift Missionary Baptist Church is scheduled to open its doors for a public memorial from 4 p.m. to 7 p.m., according to the Chicago Tribune.

Jennifer Hudson, who is also a singer, is not expected to attend the service on Sunday, as she will reportedly pay tribute to her relatives on Monday morning during an invitation-only funeral due to be held at Chicago’s Apostolic Church of God.

Guests have been asked to donate funds to the Hudson-King Foundation for Families of Slain Victims, an institution set up by Jennifer Hudson’s family for families of murder victims, instead of sending flowers.

In the meantime, investigations into the killings have advanced, as police confirmed on Friday that the gun they found close to the spot where the body of Jennifer Hudson’s 7-year-old nephew, Julian King, was discovered was the same weapon used in the murders of the boy, his 57-year-old grandmother, Darnell Donerson, and his 29-year-old uncle, Jason Hudson.

The .45-caliber gun was found on Wednesday in a vacant lot in the West Side neighborhood, not far from the place where Julian King’s body was discovered in an abandoned SUV belonging to one of the victims.

“The weapon has been positively identified through forensic examination as the weapon that was used in the homicides,” police Superintendent Jody Weis explained at a news conference, adding that authorities were “extraordinarily pleased and satisfied” with their step forward into solving the killings.

The estranged husband of Julia Hudson, Julian King’s mother, has been in police custody since police found the bodies of Darnerll Donerson and Jason Hudson on October 24 at their residence. Although 27-year-old William Balfour has not been charged, he remains a “person of interest” in the killings. He was arrested for parole violation, after spending several years in prison for attempted murder, vehicular hijacking and possessing a stolen vehicle.