11/01/2008 at 12:25 PM EDT
A handgun found near the body of Jennifer Hudson
's nephew is the same one used in the killings of the Oscar winner's family, police have confirmed.
On Wednesday, officers found a .45-caliber handgun among thick weeds in an alley about a block from where 7-year-old Julian King was discovered shot to death
inside a Chevy Suburban.
On Saturday Police Supt. Jody Weis told reporters he was "extraordinarily pleased" that tests have confirmed the gun is the same one used to kill Hudson's newphew, mother and brother,
the Chicago Sun Times
Originally, the gun was sent to the Illinois State Police crime lab for testing. Unfired bullets in the gun matched shell casings recovered at the house where Hudson's mother Darnell Donerson, 57, and brother Jason Hudson, 29, were discovered murdered
, sources told the Chicago Tribune
King was taken from the home and his body was discovered three days later in a neighborhood in another part of town, also shot with a .45, according to the paper.
Police are investigating whether the gun can be linked to William Balfour, the estranged husband of Hudson's sister Julia Hudson, sources said.
Balfour, 27, is a "person of interest" in the case. He is currently being held on an alleged parole violation stemming from his 1999 conviction on attempted murder and carjacking.
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