BRUNSWICK, Ga. - A state investigator testified Thursday that a white man was heard saying a racist slur as he stood over Ahmaud Arbery's body, moments after fatally shooting the black man with a pump-action shotgun.

The inflammatory revelation came amid a week of angry nationwide protests over law enforcement biases against black victims that erupted after the death of George Floyd in Minneapolis.

In a hearing to determine whether there was enough evidence to proceed with a murder trial, the lead Georgia Bureau of Investigation agent in the case testified that Travis and Greg McMichael and a third man in another pickup, William “Roddie” Bryan, used their trucks to chase down and box in Arbery, who repeatedly reversed directions and ran into a ditch while trying to escape.

Travis McMichael then got out of his truck and confronted Arbery, later telling police he shot him in self-defence after Arbery refused his order to get on the ground, GBI agent Richard Dial said. He said a close examination of the video of the shooting shows the first shot was to Arbery's chest, the second was to his hand, and the third hit his chest again before he collapsed in the road in a subdivision in the port town of Brunswick.

“Mr. Bryan said that after the shooting took place before police arrival, while Mr. Arbery was on the ground, that he heard Travis McMichael make the statement, `f - - - ing n - - - er,”' Dial said.

Bryan gave investigators the information roughly a week after the McMichaels' arrest, but there's no indication he told Glynn County investigators before that, Dial added.

Lee Merritt, an attorney for Arbery's family, told reporters outside the courthouse that prosecutors had warned the family before the hearing of the coming testimony about the slur.

“It was still very difficult to hear in the context of a prolonged chase, that after he murdered Ahmaud Arbery and stood over his body, he used that racial epithet,” Merritt said. The lawyer said Thursday's testimony revealed that “racism was at the heart” of Arbery's slaying.

Arbery's mother, Wanda Cooper-Jones called the release of new details in court “very, very heartbreaking.”

“He was afraid,” Cooper-Jones said of her slain son. “Life had placed him in a position where I couldn't protect him, and he wasn't able to protect himself.”

At the conclusion of the probable cause hearing Thursday, Magistrate Court Judge Wallace Harrell found that there was enough evidence for the cases against all three defendants to proceed.

“Ahmaud Arbery was chased, hunted down and ultimately executed at the hands of these men,” prosecutor Jesse Evans told the judge. “He was on a run on a public road in a public subdivision. He was defenceless and unarmed.”

Under questioning by Jason Sheffield, an attorney for Travis McMichael, Dial said Travis told police he raised his shotgun at Arbery from roughly 90 feet (27 metres) away and told him to stop and get on the ground.

That's when Arbery ran around the passenger side of Travis' truck, and the two men met in front of it.

Dial said Travis told police Arbery “squared up” like he was going to attack.

“There's a statement that he might have had his hand on his shirt,” Dial said. “Travis McMichael said his adrenaline was pumping and it all happened very quickly.”

He said Travis then fired the first shot into Arbery's chest.

Sheffield argued that the pursuit began with a legitimate concern about past crimes in the neighbourhood that escalated right before the shooting.

“Travis McMichael used self-defence when he was attacked by Mr. Arbery,” Sheffield said.

“I don't think it was self-defence by Mr. McMichael,” Dial said. “I believe it was self-defence by Mr. Arbery.”

The testimony presented Thursday raises questions about the idea that the McMichaels and Bryan were legitimately carrying out a citizens' arrest of a suspected burglar. It also could factor into a federal investigation into whether hate crime charges are warranted.

Dial testified that Greg McMichael told police that “he didn't know if Mr. Arbery had stolen anything or not, but he had a gut feeling” that Arbery had committed prior break-ins in the neighbourhood.

The investigator testified that police body camera footage showed a Confederate flag sticker on a toolbox in Travis' truck and that investigators discovered at least two more racial slurs in messages on his phone.

In response to questioning from Bryan's attorney Kevin Gough, Dial testified that he believes Bryan joined the chase because he saw a black man running down the street with a truck following and drew conclusions based on racial bias. There's evidence of Bryan's “racist attitudes in his communications,” Dial said, referring to comments found on his cellphone.

The investigator added that several residents of the subdivision where Arbery was killed told investigators they had seen him running in the neighbourhood previously.

Dial said the three defendants are the only known witnesses to the shooting and investigators have found no other video of Arbery's final moments other than what Bryan recorded.

Arbery was killed Feb. 23 after Travis McMichael, 34, and his father, Greg McMichael, 64, gave chase when they spotted the 25-year-old black man running in their neighbourhood. Bryan said he saw them driving by and joined the chase, Dial said. It wasn't until May 7 - two days after Bryan's cellphone video leaked online and stirred a national outcry - that the defendants were charged.

The McMichaels both wore masks as they sat side-by-side watching the hearing onscreen at the Glynn County jail. The judge rejected defence motions to have them brought to the courtroom, citing emergency precautions because of the coronavirus pandemic. Bryan waived his presence at the hearing.