Jennifer Hudson is expected to attend the murder trial of her ex brother-in-law today.

William Balfour is accused of killing three members of the singer's family in 2008.

The Oscar winner's mother Darnell Donerson, 57, and brother Jason Hudson, 29, were slain in the family home with her nephew Julian King, seven, found murdered in a car three days later back in October 2008.

It is understood Jennifer's sister Julia, the ex-wife of the suspect, is to be the star witness in the Chicago courtroom today as opening statements begin.

William faces a life sentence for three counts of first-degree murder, aggravated kidnapping and home invasion.

Prosecutors have said he was angered when he believed balloons at the Hudson family home were sent to Julia by another man.

William is suspected of threatening to kill the family on at least two occasions before the incident. He allegedly stole a .45-caliber handgun from Jennifer's brother and used it in the killings.

The 30-year-old was on parole at the time for attempted murder and a vehicular hijacking conviction.

There are no witnesses in the incident but previous reports have suggested Jennifer may take the stand to testify.

Prosecutors filed papers in court last month which contained interviews detectives carried out with the Dreamgirls star after the tragedy.

The paperwork states that Jennifer knew the suspect from when she was a child but advised her sister not to marry him.