Prosecutors: Balfour's Jealousy Led to Hudson Family Murders

Authorities offer motive, claim Jennifer Hudson's estranged brother-in-law was irate over gift to former wife

Finally a motive in the murders of Jennifer Hudson's family.

Prosecutors in Chicago today confirmed the theory they laid out in a hearing earlier this month that the Oscar winner's estranged brother-in-law was caught in a fit of jealous rage when he murdered Hudson's mother, brother and nephew.

In court papers obtained by E! News, the Cook County State's Attorney's Office allege that at about 8:10 a.m. on Oct. 24, William Balfour stopped by the residence he had shared with Julia Hudson until their separation in February. Balfour allegedly went ballistic after seeing a birthday present he wrongly assumed had been given to Hudson by a new beau.

"Defendant again warned Julia Hudson about having a relationship with another man," the court papers read. Prosecutors say Balfour repeatedly had threatened to harm his ex-wife's family, but because he never acted out before, she wasn't overly concerned.

Jennifer and Julia Hudson's mother, 58-year-old Darnell Donerson, their 29-year-old brother, Jason Hudson, and Julia's 7-year-old son, Julian King, were asleep in the house at the time. Julia Hudson left the house to go to work, while Balfour reportedly went to a gas station to deal with some car trouble.

But, per prosecutors, at some point Balfour returned to Hudson's home, this time packing a gun he had swiped from Jason Hudson. Balfour allegedly shot Darnell in the living room, Jason in a bedroom and then left with Julian in a white Suburban. Balfour shot the boy as he was crouched behind the front seat, the prosecutors allege.

Balfour was charged with three counts of first-degree murder and one count of home invasion and is currently being held without bail. His next hearing is scheduled for Dec. 30.

—Reporting by Ashley Fultz