Under cross-examination, Julia Hudson acknowledged she was still having sex with Balfour days before the slayings,
The killings happened the day after her birthday. Prosecutors say Balfour became enraged by balloons he saw at the home that he thought were from her new boyfriend.
Defense Attorney Amy Thompson suggested to jurors during opening statements that the killings may have stemmed from alleged drug dealing by Jason Hudson in the impoverished, crime-ridden South Side neighborhood where they lived. Police, she told jurors, pinned the slayings on Balfour because they felt pressured to make an arrest.
"As soon as that (that a celebrity was linked to the case) became known, they knew coverage would explode," Thompson said. "The police were on the hook. They had to find their man and find him fast."
Prosecutors say Balfour went inside the three-story house around 9 a.m. and used the handgun to kill Hudson's mother, 57-year-old Darnell Donerson, in the living room, and then shot her 29-year-old brother, Jason Hudson, twice in the head as he lay in bed.
He allegedly drove off in Jason Hudson's SUV with Julian inside. Authorities say he shot the boy in the head as he lay behind a front seat.
There are no known witnesses to the slayings, and it's unclear what physical evidence exists, including fingerprints or DNA. During her opening statement, Thompson said DNA found on the gun and fingerprints found in the SUV didn't match Balfour's.
If convicted of at least two of the murder counts, the 30-year-old Balfour would face a mandatory life sentence.
Associated Press writer Don Babwin contributed to this report.
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