A Chicago jury on Friday convicted Oscar-winner Jennifer Hudson’s former brother-in-law of murdering her mother, brother and 7-year-old nephew in what prosecutors’ described as an act of vengeance by a jilted husband.

Hudson, who expressed her undisguised disdain for William Balfour when she took the witness stand and who endured weeks of excruciating testimony about the October 2008 killings, was visibly overcome with emotion as the verdict was read. Hudson’s eyes filled with tears and she shook her head and bit her lip. Afterward, she looked over at her sister, Julia Hudson, and smiled.

Balfour, who faces a mandatory life prison sentence, showed no emotion.

Jurors deliberated for three days before reaching their verdict against Balfour, a 31-year-old former gang member who was the estranged husband of Hudson’s sister at the time of the triple murders.

With no surviving witnesses to the Oct. 24, 2008, slayings or fingerprints, prosecutors built a circumstantial case against Balfour by calling 83 witnesses over 11 days of testimony. Witnesses said he threatened to kill the entire family if Julia Hudson spurned him.

Balfour’s attorneys proposed an alternate theory: that someone else in the crime-ridden neighborhood on Chicago’s South Side targeted the family because of alleged crack-cocaine dealing by Jennifer Hudson’s brother, Jason Hudson. During the 30 minutes in which they called just two witnesses, however, they presented no evidence to support that theory.

Public defender Amy Thompson said she would appeal the verdict.