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Jennifer Hudson broke down on the witness stand Monday during the Chicago trial of William Balfour, the man accused of killing the Oscar winner's mother, brother and nephew in 2008.

Hudson -- who wore a black dress and her hair wrapped in a bun -- was the first witness called to testify after both sides presented opening arguments. She responded to prosecutors' questions softly but confidently and when asked to identify the defendant, she pointed at Balfour and said: "He's sitting right there." The defendant showed little emotion during the proceedings.

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Hudson then fought back tears as she told jurors how she reacted when her sister told her she was going to marry Balfour. "None of us wanted her to marry him. We did not like how he treated her." After about 30 minutes on the stand, Hudson grabbed a handful of tissues and walked slowly across the courtroom in front of jurors before taking a seat in the fourth row next to her fiancé, David Otunga.

Julia Hudson, Jennifer's sister, later took to the stand to testify against her estranged husband, telling jurors that Balfour at times became angry when her son, Julian King, kissed his mom. Julia also identified the murder weapon as her brother's gun that Balfour allegedly stole months before the killings.

Balfour has pleaded not guilty to three counts of first-degree murder in the October 2008 slayings. Prosecutors allege the suspect shot the family members in a jealous rage because Julia Hudson was dating another man.

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Prosecutor Veryl Gambino said during his opening statements that Balfour began threatening to harm the family shortly after moving out of Hudson's family home. "Those were not idle threats. They were deadly warnings of what was to come," he told the jury.

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Defense Attorney Amy Thompson portrayed a different view of the killings, telling jurors that police pinned them on Balfour because they felt pressured to make an arrest. "As soon as that (celebrity link 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."