Hudson sat next to her fiancé as prosecutors shifted their focus to presenting crime scene evidence in the case against her former brother-in-law, William Balfour.
Hudson hung her head and shut her eyes as Chicago police Sgt. David Dowling described finding her mother's body sprawled in the living room with gunshot wounds through her back.
Hudson didn't move as Dowling described finding her brother dead in his bed of a gunshot wound to the head. His sheets were pulled up as if he had been sleeping.
Balfour was estranged from his wife, Hudson's sister, at the time of the killings. He has pleaded not guilty to murdering Hudson's mother, brother and 7-year-old nephew.
Hudson, wearing a black top and green skirt, sat in a fourth row bench well within view of jurors Tuesday. Her sister and Balfour's ex-wife, Julia Hudson, sat on her left.
Another officer testified about the frantic search for Hudson's nephew, who was found in an SUV three days later. Prosecutors also played a surveillance video showing Balfour getting out of a car at a gas station near the Hudson house on Chicago's South Side before the killings. Prosecutors are trying to show he was in the area at the time - something Balfour has denied.
As the video played on a courtroom screen, Jennifer Hudson rested her head on her knees for several minutes.
Prosecutors created a buzz Monday by calling the Oscar winner and "American Idol" finalist as their first witness, but on Tuesday they began getting down to the nitty-gritty of their case.
With no surviving witnesses to the murders, prosecutors must offer overwhelming circumstantial evidence that Balfour committed the grisly crime on Oct. 24, 2008.
One challenge will be tying Balfour to the alleged murder weapon, a silver and black .45-calibre handgun that sat Monday on a stack of papers at the prosecution table in plain view of jurors and Jennifer Hudson.
Public defender Amy Thompson told jurors during her opening statement that DNA found on the gun didn't match Balfour, which "absolutely, positively" excludes him as the killer.
But prosecutors claim Balfour targeted the family in a horrific act of vindictiveness against his ex-wife. They believe he became enraged by balloons he saw at the home that he thought were from her new boyfriend.
Prosecutors contend Balfour went inside the three-story house around 9 a.m. and shot Hudson's mother, 57-year-old Darnell Donerson, in the living room, then shot her 29-year-old brother, Jason Hudson, twice in the head as he lay in bed.
Investigators allege he then drove off in Jason Hudson's sport utility vehicle with Julia Hudson's 7-year-old son, Julian King, inside, and later shot the boy in the head as he lay behind a front seat.
Shortly after Thompson and prosecutors laid out their cases, Jennifer Hudson took the witness stand in sometimes tearful, gut-wrenching testimony. Hudson, who was in Florida at the time of the shootings, spoke of her family and her reaction to her sister, Julia Hudson, telling her in 2006 that she was marrying Balfour.
"None of us wanted her to marry him," the 30-year-old said, her voice cracking as she struggled to hold back tears.
Later, Julia Hudson described how Balfour repeatedly threatened her and her family after she rejected his pleas in May 2008.
If convicted of at least two of the murder counts, Balfour would face a mandatory life sentence.