Authorities investigating the shooting deaths of Jennifer Hudson's mother and brother spent Saturday searching for the Oscar-winning actress' 7-year-old nephew, still missing despite an Amber Alert issued Friday.

Neighbors, friends and family gathered Saturday outside the three-story white house on the city's South Side where Hudson went to school and sang in church. Some left stuffed animals and flowers, and others planned a search for young Julian King.

"We need to find that kid by sundown," Ziff Sistrunk, a friend of the Hudson family, said Saturday.

A potential suspect in the deaths was in custody Friday night, but King had not been seen since the bodies of Darnell Donerson, 57, and Jason Hudson, 29, were found Friday afternoon. The FBI is working on the case with local authorities.

A family member entering Donerson's South Side home Friday afternoon found the woman shot on the living room floor. Officers later found Hudson shot in the bedroom, police said.

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At least one of the victims suffered defensive wounds, said authorities who described the shooting as domestic violence.

William Balfour, who is being questioned in the deaths, was arrested Friday but had not been charged, law enforcement sources told the Chicago Tribune and Chicago Sun-Times.

Police spokeswoman Monique Bond said investigators were talking to "a number of people in custody" but she declined to elaborate. An alert issued Friday said Balfour was a suspect in the double homicide.

Balfour was married to Hudson's sister, Julia, for several years but they were separated, said his mother, Michele Balfour. She said Donerson had ordered him to move out of the family's home last winter.

Authorities would not confirm the identity of Julian King's parents, but family friends said he is Julia Hudson's son. There was no immediate word on the identity of the missing boy's father.

Jennifer Hudson's personal publicist, Lisa Kasteler, said the family wanted privacy.

Records from the Illinois Department of Corrections show Balfour, 27, is on parole and spent nearly seven years in prison for attempted murder, vehicular hijacking and possessing a stolen vehicle. Public records show one of Balfour's addresses as the home where Donerson and Jason Hudson were shot.

The Cook County medical examiner's office said autopsies were being conducted Saturday morning, but results would not be available until later in the day.

The tragedy comes as Jennifer Hudson, who grew up in Chicago, continues to reach new heights in her career. Her song "Spotlight" is No. 1 on Billboard's Hot R&B/Hip-Hop charts and her recently released, self-tiled debut album has been a top seller. She was featured in this year's blockbuster "Sex and the City" movie and is also starring in the hit film "The Secret Life of Bees."

She won an Academy Award for best supporting actress in 2007 for her role in "Dreamgirls." In an interview last year with Vogue, Hudson credited her mother with encouraging her to audition for the TV singing competition "American Idol," which launched her career.

The singer, whose father died when she was a teenager, described herself as very close to her family. In a recent AP interview she said her family, which includes older siblings Julia and Jason, helped keep her grounded.

"My faith in God and my family, they're very realistic and very normal, they're not into the whole limelight kind of thing, so when I go home to Chicago that's just another place that's home," she said. "I stand in line with everybody else, or, when I go home to my mom I'm just Jennifer, (so she says), 'You get up and you take care of your own stuff.' And I love that; I don't like when people tell you everything you want to hear, I want to hear the truth, you know what I mean."

Hudson recently announced her engagement to David Otunga, best known for his stint on VH1's reality show "I Love New York."

Hudson's representatives would not disclose her whereabouts Friday. She had been scheduled to appear Monday in Los Angeles to collect an ensemble cast honor at the Hollywood Awards for "The Secret Life of Bees" with co-stars including Alicia Keys, Queen Latifah and Dakota Fanning.

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