A jury has found Jennifer Hudson's former brother-in-law William Balfour guilty of murdering her mother, brother and seven-year-old nephew.

Balfour, 31, was found guilty of three counts of murder and four other counts related to the 2008 killings and he now faces a mandatory sentence of life in prison.

He had pleaded not guilty to shooting to death the singer's mother Darnell Donerson, 57, her brother Jason Hudson, 29, and her seven-year-old nephew Julian King on October 24, 2008, as well as home invasion, residential burglary and possession of a stolen vehicle related to the killings.

His attorney argued there was no forensic evidence linking him to the murders.

The panel took 18 hours deliberating on the case after it went to the jury yesterday (10.05.12) at Cook County Court in Chicago, before finding Balfour guilty of triple murder.

The 'Dreamgirls' actress - who attended every day of the testimony - arrived at court shortly after it was revealed that the jury had reached a verdict.

The jury's verdict was finalised just hours after the panel of six men and six women told Judge Charles Burns of Cook County Court that they had come to a split decision, but they were going to continue deliberating.

In prosecutor Jennifer Bagby's closing argument she showed autopsy pictures of the victims and then pointed at Balfour and said: ''It's time to hold him responsible.''

During the case prosecutors presented evidence showing Balfour - who was on parole at the time of the deaths - had a gun, was at Jennifer's family home the morning of the murders and threatened to kill the family on a number of occasions, despite there being a lack of DNA or fingerprint evidence directly linking him to the killings.

But Balfour's defence team claimed police and prosecutors had created a story to implicate him.

In her closing statement on Wednesday (09.05.12), Balfour's lawyer Amy Thompson claimed the real murderer was likely to be an enemy of Jason, who the defence alleged had dealt DRUGS in the neighbourhood and been shot and wounded before.

She said: ''In their mind, this wasn't a whodunit.''

Prosecutors previously claimed a gift of balloons sent to Jennifer's sister Julia threw him into a jealous rage, causing him to use a .45 caliber handgun to kill 57-year-old Darnell, Jason and Julian, whose body was found three days later.

The Oscar-winning actress was the first person to testify at the trial and in an emotional appearance in court she revealed she had told her sister Julia not to marry Balfour.