­Prosecution and defence lawyers clashed during angry closing arguments in the trial of the man accused of killing relatives of singer and actress Jennifer Hudson.

During the heated exchanges, William Balfour’s lawyer told jurors that prosecutors had failed to prove their case.

The state’s lawyers hit back, saying that the defence was clearly desperate in the face over overwhelming evidence.

Actress and singer Ms Hudson sobbed and dabbed her eyes when prosecutors displayed photos of the bullet-riddled bodies of her mother, brother and seven-year-old nephew at the Chicago trial.

Prosecutors say Mr Balfour, Ms Hudson’s former brother-in-law, killed the family members in October 2008 in an act of vengeance against Ms Hudson’s sister Julia, to whom he was married but estranged at the time.

With no surviving witnesses, prosecutors have spent two weeks laying out a largely circumstantial case against Mr Balfour, a 30-year-old one-time gang member.

Public defender Amy Thompson seized on that during her closing argument, saying prosecutors had failed to meet their burden of proving Mr Balfour was the killer.

“They know as they sit there that they have failed to prove the case,” Ms Thompson said, almost shouting. “I am offended that they would ask you to throw your logic away.”

In a scathing final word to jurors on Wednesday night before they began deliberations, lead prosecutor James McKay said that for jurors to believe Mr Balfour was innocent they would have to believe he was just unlucky enough to have someone else kill the Hudsons after he himself had threatened to murder them at least 25 times, as witnesses had said.

“I want to introduce you to, William Balfour, the MegaMillions winner of bad luck,” he said.

“But Mr Innocent here did everything a guilty man would do”, including lying about his whereabouts and getting rid of the clothes he wore on the day of the triple murders.

Mr McKay at times gritted his teeth, snarled and pointed at Balfour, who denies three counts of first-degree murder.

At one point, he walked up to look directly at Mr Balfour from a few metres away. His voice soaring, Mr McKay boomed: “Calling the defendant a dog is an insult to dogs”!

The comment prompted a buzz among spectators and objections from the defence.

Earlier in the day, prosecutor Jennifer Bagby displayed photographs of the victims smiling for a camera. A second later, she flashed photos of their blooded, bullet-ridden bodies.

“This defendant is the one that made (them) into these images,” Ms Bagby said, glancing back at the photos.

Ms Hudson bent forward, her head on her knee, crying. Her fiancé, wrestler David Otunga, put his arm around her, rubbing her neck.

Ms Thompson argued that DNA recovered from the alleged murder weapon, a .45-calibre handgun, and on the steering wheel of Balfour’s car did not match her client’s.

“The only person who we know for sure didn’t do it in Chicago,” she said, “was William Balfour”.

Ms Thompson also made the same argument she made in her opening, that all the evidence was circumstantial and no witness could place her client at the scene of the murders.

But Mr McKay told jurors that the defence was exploiting a popular misunderstanding about the meaning of circumstantial evidence.

“Circumstantial evidence isn’t just as good as direct (witness) evidence. It’s better,” he said, saying it was not subject to human interpretation.

The circumstantial evidence against Mr Balfour had become “a tsunami of evidence ... that is drowning him in guilt”, he added.

Mr McKay also lashed out at Ms Thompson, who had finished her closing statements minutes earlier.

“I don’t know what the acoustics are like in this courtroom,” he shouted, “but what in the world was she listening to here (during two weeks of evidence)?”

Starting her closing statements, Ms Bagby laid the alleged murder weapon on the podium, the silver and black handgun. She said gunshot residue from the weapon was found on the steering wheel of Mr Balfour’s green Chrysler and bullets taken from the bodies were fired from the same gun.

If convicted on all counts, Mr Balfour faces a mandatory life prison term. Prosecutors presented 11 days of evidence and called 83 witnesses, starting with Ms Hudson. She told jurors about the last time she saw her three family members alive and spoke with disdain about Mr Balfour, whom she had known since school.