Jennifer Hudson, dressed all in black and wearing little makeup, struggled at times to maintain her composure on the witness stand Monday as the trial of her former brother-in-law opened in dramatic fashion.

Her voice cracked as the Academy Award-winning actress described how no one in the family wanted her sister, Julia, to marry William Balfour, accused of killing Hudson's mother, brother and 7-year-old nephew.

"We didn't like the way he treated her, and I didn't like the way he treated my nephew," she testified.

Balfour is accused of fatally shooting Hudson's mother, Darnell Donerson; brother Jason Hudson; and nephew, Julian King, in October 2008 after Julia Hudson told him that she wanted a divorce.

Jennifer Hudson's emotional testimony offered little insight into the slayings but gave prosecutors a chance to put a heartbroken — and familiar — face on a gritty South Side crime. Her presence gives an important advantage to the prosecution, who will present a largely circumstantial case during the expected monthlong trial.

Earlier Monday, the defense addressed her star power quickly during opening statements, saying the heavy media interest after the slayings prompted authorities to arrest Balfour without a proper investigation. There is no DNA, fingerprints or gunshot residue connecting Balfour to the slayings, according to his attorneys.

With so much attention focused on the Chicago icon in the days after the slayings, police did not look into allegations of drug dealing involving Jason Hudson or the people he associated with, Public Defender Amy Thompson said. Jason Hudson, 29, who had been arrested on drug charges in the past and had been shot on two other occasions, brought an element of danger to the home, she maintained.

"This really had nothing to do with (Jennifer Hudson)," Thompson told jurors. "It was what Jason was doing to make money for their family ... as he worked as a drug dealer in Englewood."

Hudson's presence, however, could not be ignored in the Cook County courtroom as jurors listened intently to her testimony. She appeared soft-spoken and vulnerable on the witness stand, answering questions so quietly that the judge asked her more than once to speak up.

She spoke fondly of her mother as she told the jury that Donerson texted or called her every morning because she worried about her youngest child being out in the world alone. Hudson sheepishly told that jury that she had slept in her mother's bed until she was 16.

Hudson broke down in tears when prosecutors asked her to identify a photograph of her mother taken at Donerson's last birthday.

"That's my mommy," Hudson whispered.

Given their frequent contact, Hudson found it odd when she woke up the morning of Oct. 24, 2008, and did not have a text message waiting from her mother.

In a halting voice, she recalled receiving a frantic phone call from her sister hours later and told how she flew back immediately to Chicago to identify the bodies of her mother and brother at the morgue. She offered a $100,000 reward for her nephew, who was still missing at that time.

"We were trying everything, anything we could do to get him back," she said.

Two days after posting the reward, Hudson returned to the morgue again after Julian's body had been discovered on the West Side in a vehicle stolen from the Hudson home.

Hudson remembered happier times spent with her nephew, whom she affectionately called "Tugga Bear."

Hudson also spoke about how she used her newfound fame to help her family. In the months before the slayings, Hudson bought her sister a computer and her brother a car and left her mother numerous signed checks to pay utility and other bills.

After a half-hour on the witness stand, Jennifer Hudson joined her fiance, Chicago lawyer-turned-professional wrestler David Otunga, in the courtroom gallery to listen to her sister's testimony. She clutched a handkerchief in her left hand as she sat with her head slightly bowed.