Police recovered a gun Wednesday in an alley near where Jennifer Hudson's nephew was found shot to death inside a sport utility vehicle on the West Side, NBC News reported.
It was not immediately known whether the gun was used in the killings of Hudson's mother, brother and nephew.
Law-enforcement sources told the Chicago Tribune that more than one person might have been involved in the killings, even as police remain focused on the estranged husband of her sister.
All three victims were shot to death. Her 7-year-old nephew, Julian King, was shot twice in the head with a .45-caliber weapon, the same caliber used in the slayings of his uncle and grandmother, law enforcement sources told NBC News.
Officers blocked off the alley after the discovery and a forensic services team was sent to recover the weapon. Police had no additional comment.
Balfour remains jailed
Investigators are trying to determine whether another person drove William Balfour to the West Side of Chicago after the killings at the Hudsons' South Side home, the sources said. Balfour remains jailed on unrelated charges as police search for clues.
Witnesses said Balfour drove his vehicle to the Hudsons' block on Friday around 7 a.m., yet police found it later parked about a mile away outside a high school on the South Side, the Tribune reported.
Security video at the South Side school shows someone parking the vehicle on Friday, but investigators have not been able to determine the person's identity, the sources said. A time stamp on the video showed the car was parked at 12:30 p.m., but it was unclear if the stamp was accurate, the sources said.
Cell phone records placed Balfour on the West Side at that hour, the sources noted. If the time stamp is accurate, it would suggest another person may have driven his vehicle from the Hudson home to the school.
In any event, Balfour did not use his own car to travel from the Hudson's home to his girlfriend's home on the West Side, police said.
Balfour's girlfriend told police that he was at her West Side home not long after the slayings of Hudson's mother, Darnell Donerson, and Jason Hudson at their home on Friday, the sources told the Tribune.
The body of Hudson's 7-year-old nephew, Julian King, was found Monday in the back of Jason Hudson's vehicle, which was parked on a West Side street.
Arrested in June
On Tuesday, parole records showed that Balfour could have been spending the past few months behind bars for a parole violation after being arrested in June for what police said was a rock of cocaine on the driver's seat of his car.
The 27-year-old felon was instead allowed to remain free.
Moreover, Balfour told his parole agent he had missed a meeting last Friday because he was baby-sitting, records show.
No one has been charged in the killings. An Amber Alert issued on Friday named Balfour as a suspect in the deaths of Donerson and Jason Hudson.
The Illinois Department of Corrections issued a warrant for Balfour on Saturday for violating terms of his parole by possessing a weapon and failing to attend anger management counseling and a substance abuse program, according to his parole report.
Now that Balfour is in custody, detectives have time to dig deeper into his life, including his relationship with his ex-wife, Jennifer Hudson's sister Julia, and his exact whereabouts during the weekend.
Attempted murder conviction
Balfour was paroled after serving seven years for a 1999 attempted murder and vehicular hijacking conviction.
On June 19, police pulled over Balfour's car after hearing gunshots in the area, according to the officers' report. They found a rock of cocaine in plain view on the driver's seat, the report stated. It had a street value of about $100.
A parole supervisor declined to issue a warrant to revoke Balfour's parole after the arrest, records show.
"Per supervisor ... no warrant," the report reads. "Agent to monitor offender, impose sanctions."
Corrections Department spokesman Derek Schnapp said officials who reviewed the cocaine-possession case against Balfour determined "the evidence that was presented during that time wouldn't have necessarily warranted a violation."
Parole could have been revoked
A judge dismissed the charge for lack of probable cause in July, though no reason was cited in court records.
However, a felony arrest usually is sufficient reason for corrections officials to revoke parole, said Thomas Peters, a Chicago criminal defense attorney who represents parolees.
"Even though the criminal case is dismissed does not mean that you necessarily get a pass on a parole violation because the standard of proof is much less," he said.
In Balfour's case, a parole violation could have sent him back to prison for as long as the remainder of his parole — until May 2009 — minus a day off for each day of good behavior. That would have meant a release date in mid-December at the earliest.
Balfour's parole history also shows that a woman at Balfour's home refused to open the door during an agent's visit on Aug. 27. The woman told the agent during the 8:30 a.m. visit that Balfour was at work but Balfour's boss told the agent he wasn't due until noon.
"Agent heard other people inside the host site and suspected maybe suspicious activities going on," the report said. "Agent will be following up for a possible warrant on parolee."
Parolees must agree to allow agents to visit their homes and consent to searches. There's no warrant mentioned in following days on the report, which does note, however, that Balfour passed a drug test.
Schnapp said the evidence again wasn't sufficient to warrant revoking parole.
Jennifer Hudson, who won a best-supporting-actress Oscar last year for "Dreamgirls," has thanked fans for their support on her MySpace page but has been in seclusion in Chicago.