CHICAGO (CBS) — A friend of the man charged with killing Jennifer Hudson’s family members may have helped prosecutors fill in some gaps in their case on Monday, telling jurors about a panicked phone call he got from William Balfour on the day of the murders.

CBS 2’s Dana Kozlov reports Quincy Jones, a convicted felon serving time in federal prison, came across as a believable witness despite wearing an orange prison jumpsuit on the stand.

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Brown testified he saw Balfour with the murder weapon just days before Hudson’s mother, brother and nephew were killed. He also said he got a call from Balfour on the day of the murders, a conversation in which Balfour seemed to be in a “panic.”

Balfour, 30, is accused of killing 57-year-old Darnell Donerson, 29-year-old Jason Hudson, and 7-year-old Julian King on Oct. 24, 2008. Prosecutors have said Balfour was in a rage, because his estranged wife, Julia Hudson — Jennifer’s sister — was dating another man.

Brown told jurors Monday that he met Balfour in the summer of 2008, describing him as a close friend who at least twice threatened to kill Julia Hudson, or her brother Jason. Several other witnesses have testified Balfour repeatedly threatened to kill Julia and her family.

But Brown did something no other witness had done until Monday – testify he saw Balfour with the murder weapon three days before the murders.

Brown said he and Balfour – whose nickname was ‘Flex’ – were with friends, playing cards, when Balfour suddenly pulled out the gun, slammed it on a table, and yelled about how much he hated JasonHhudson.

Less than three days later, Hudson and his relatives were dead. Prosecutors have said Balfour used a gun he allegedly stole from Jason Hudson.

Brown identified the same gun in court, saying it was the “.45 black and gray gun that Flex used to own.”

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Brown also said an agitated Balfour called him on the afternoon of the murders, asking him to get Balfour’s car and move it to the West Side.

At one point, Brown said Balfour took a call from Julia Hudson, who asked Balfour why he’d killed her mother and brother. At that point, Julian King’s body had not yet been found.

“Are you for real?” Brown testified he asked Balfour.

Brown said Balfour said yes, and when he asked Balfour why, his friend said “because I got into it with that b****h a** n****r,” a term he’d used before to describe Jason Hudson.

In a later call with Balfour, Brown testified, “I asked him boldly, did he do it? He said, ‘It’s bigger than me,’ and that’s when he hung up.”

Brown also testified Balfour frequently wore baseball-type gloves in the summer of 2008, which would help explain why none of his fingerprints or DNA were on the murder weapon, or in Jason Hudson’s SUV, where Julian’s body was found three days after the murders.

Brown said he received no special consideration or leniency from prosecutors in exchange for his testimony. He also acknowledged that he did not tell his story to investigators until they approached him last year.

There were some inconsistencies, though. Prosecutors said in opening statements that Balfour called Julia on the day of the murders, not the other way around.

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Late Monday afternoon, prosecutors also played the video recording of Balfour’s interview with police.