The trial began on April 23 in Chicago. Prosecutors called more than 80 witnesses over two weeks, and the defense rested its case after 30 minutes, calling only two witnesses to the stand. Balfour did not testify.
Prosecutors alleged that Balfour fatally shot Hudson's mother, Darnell Donerson, 57, in her living room, and then shot Hudson's brother Jason Hudson, 29, as he lay in bed. He then kidnapped Hudson's nephew Julian King, who was 7. Investigators believe the boy was shot in the head as he lay behind the front seat of an SUV.
Prosecuting State Attorney Veryl Gambino said Balfour was in a state of rage over Julia Hudson's dating another man, and said Balfour had issued several threats against her and her family. Balfour allegedly was enraged on Oct. 24, 2008, after he saw balloons another man sent to Julia Hudson and punched them.
Julia Hudson found her mother's body in her home and initially thought she had fallen. It wasn't until she saw blood that she realized something worse had taken place. Julia Hudson ran screaming from the house and called 911.
The killings happened in the family home in Chicago's tough Englewood neighborhood, where Jennifer Hudson grew up.
In Assistant State Attorney Jennifer Bagby's closing arguments, she said that Balfour "was fueled by his obsession, his jealousy, his determination to catch his wife, Julia Hudson, with another man. She didn't want him around, her family didn't want him around. But in his mind, she was his wife, and if he couldn't have her, no one could."
Bagby punctuated her narrative by frequently quoting Balfour's allegedly repeated threat to his estranged wife: "If you leave me, I will kill you. I will kill your family first. You will be the last to die."
While the defense argued no physical evidence linked Balfour to the murders, prosecutors spent significant portions of their closing arguments focusing on what they said was important physical evidence in this case.
The evidence included cellphone records that put Balfour near the scene at the time of murders, gun residue found on Balfour's clothing and on the steering wheel of his car, and the key to Jason Hudson's SUV found on Balfour when he was arrested.
Prosecutors spoke about the "overwhelming circumstantial evidence."
Balfour's attorneys say there is no evidence or DNA linking him to the murders.
Thompson said in her closing arguments that police "weren't trying to figure this out. They had their man. They spread it across the news. They were just trying to prove it by building a case any way they could."
Thompson emphasized that Balfour's fingerprints were not found on the gun or the car where Julian was killed.
"The one constant in this case is that every piece of DNA evidence absolutely excludes William Balfour," Thompson said. "The one person in all of Chicago who didn't do it is him. That's what the evidence showed."
The Associated Press contributed to this report.