A friend of Jennifer Hudson says he tried to warn the family about William Balfour, who is currently the main “person of interest” in the shootings of Hudson’s mom, Darnell; brother, Jason and 7-year-old nephew, Julian King.

William Balfour, a.k.a. “Flex” – who’s divorced from Hudson’s sister, Julia, a bus driver – got into a huge fight with Julia, Darnell and Jason about a month ago, a neighbor says. James Peyton, Hudson’s ex-fiance, was also present.

“Flex tried to start a fistfight with Jason, and James beat up Flex,” the neighbor tells Us Weekly, which features the Hudson family murders on its cover.

Shortly after, Balfour began to threaten the family, saying “he would kill Julia and mess up everyone inside the house.” One supposed reason for the feud? Julia claimed that Balfour sold one of their cars without permission.

“Flex was crazy, but Jason never took him seriously,” the source said. “Jason always thought he would be safe, that he could protect himself.”

 The estranged couple had screaming matches, and had “been having problems, but I never expected anything like this,” neighbor Angela Russell said.

William Balfour is currently being held on violation of parole stemming from an attempted murder conviction in 1999. The AP reports that he was arrested on June 19 for allegedly having a rock of crack cocaine in his car.

Interestingly his parole was not revoked then.

Meanwhile, Jennifer Hudson is determined to hold her family together as she grieves for her mother, brother and nephew – whom she was especially close to.

“Jennifer was like a second mom to [Julian King],” Ernest Moore, a Chicago neighbor related to the Hudsons by marriage, said.

“Whenever she was around, she spent a lot of time with the boy.”

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