LOS ANGELES, CA - FEBRUARY 12:  Singer Jennifer Hudson performs onstage at the 54th Annual GRAMMY Awards held at Staples Cent
Jeff Kravitz

The heartbreaking tragedy of the murder of Jennifer Hudson's family is once again in the public eye with the start of William Balfour's trial. Balfour, the ex-husband of Jennifer's sister Julia, is accused of murdering Hudson's mother, older brother and 7-year-old nephew (his stepchild). 

The Oscar-winning actress and soul singer was the first witness to take the stand on Monday, April 23. She testified she had always been against her sister marrying Balfour, who she had known since middle school. "I would tell [Julia] over and over again not to marry William," Hudson told the court. "We didn't like the way he treated her, and I didn't like the way he treated my nephew," she said.

William Balfour's Police Booking Photo

CHICAGO, ILLINOIS - APRIL 18: In this handout image provided by the Cook County Sheriff's Department, William Balfour is seen
Cook County Sheriff's Department Handout

Hudson's mother Darnell Donerson, 57, brother Jason Hudson, 29, and nephew Julian King, 7, were found murdered in October 2008. Darnell and Jason were found shot in the family's Chicago home, and 7-year-old Julian was found shot to death several days later in a stolen SUV.

The prosecution alleges Balfour was dangerously jealous of his wife and made repeated threats to kill her and her family, but no one realized how dire the warnings were at the time. Just last year, Julia was granted a divorce from Balfour by the courts. 

After Jennifer took the stand, Julia Hudson testified the gun used in the murders was her late brother's, and the firearm had been stolen by her ex-husband months prior to the killings.

Jennifer Hudson is expected to be present for most of the trial.