Singer and Oscar-winning actress Jennifer Hudson is set to make a dramatic appearance in court as the trial of her murdered mother, brother and nephew begins Monday. Jennifer, 30, could play a key role in the Chicago murder trial of her slain family, including murdered mother, Darnell, brother Jason and seven-year-old nephew, Julian. Prosecutors say William Balfour, the estranged husband of Hudson's sister Julia, murdered the three family members in a fit of jealous rage as she had started dating another man. The bodies of mother Darnell Donerson, 57, and brother Jason Hudson, 29, were found in the family's home in the Engelwood neighbourhood of Chicago in 2008. Jennifer's nephew, Julian, was found days later in a vehicle several miles from the family home. But the star's presence at the trial means would-be jurors are set to face strong questioning from the judge amid legal fears that she could have an impact on the trial. Ms Hudson is expected to be at the trial every day once testimony begins and she is on a 300-strong list of witnesses who could give evidence at the trial. Judge Charles Burns will start questioning those wishing to make the jury Monday, trying to eliminate anybody who could be affected by the star's presence. Prospective jurors will face strong questioning, including whether they watched her on American Idol, belong to Weight Watchers, the dieting company where Hudson has been a spokeswoman for several years and if they have read her book. The difficulty confronting the judge became clear when many jurors gasped when he read the name of the case. Gerald Uelman, a defense attorney at O.J. Simpson's trial, said: 'The risk is that jurors may be watching her rather than testifying witnesses, and they could be influenced by how she reacts. 'She would be well advised not to engage in any facial expressions or outbursts. That could be grounds for a mistrial.' Accused ex-gang member Balfour has a known history of violence and a criminal record. His attorneys say the evidence is circumstantial, but prosecutors claim the proof he committed the crime include gun residue found on his car's steering wheel. He once belonged to the Chicago-based Gangster Disciples and known by his street name 'Flex', according to court documents. In preliminary questioning, 20 potential jurors stood up when the judge asked if they couldn't hear the evidence 'without sympathy, bias or prejudice'. Judge Burns finally told them to ignore the question for the time being. Ms Hudson said she knew something was wrong on the morning of October 24, 2008, when she couldn't reach her mother - whom she spoke to daily - according to documents filed by prosecutors. She was interviewed by police shortly after the bodies of her mother and brother were discovered. The singer then offered a $100,000 reward for the safe return of her nephew before he was found days later on the west side of the city in an abandoned vehicle with multiple gun shot wounds. Under questioning from police investigators, Ms Hudson revealed she had known Balfour since childhood and had been against her sister marrying him. Balfour once allegedly threatened to kill her sister because he believed she was having an affair with a colleague, Ms Hudson told police. The singer has referenced the heartbreak over the murders, but has never talked about the 2008 killings in great detail. Jennifer shot to fame on American Idol in 2004 when she made the final three of the show and could appear on the Fox talent programme this Thursday. She has since been endorsed by Weight Watchers and signed a $1million book deal after slimming down significantly from her rounder figure. Her memoir I Got This: How I Changed My Ways and Lost What Weighed Me Down was published in January.