Special agent Richard Dial of the Georgia Bureau of Investigation (GBI) quoted William Bryan as saying Travis McMichael uttered the slur after shooting Ahmaud Arbery in February.
Bryan and McMichael are both defendants in the case.
“Bryan said that after the shooting took place before police arrival, while Arbery was on the ground, he heard Travis McMichael make the racial slur,” Dial said in testimony in front of a Glynn County judge.
The Arbery case triggered a national outcry after cellphone video of the February 23 shooting was leaked on social media.
Yesterday’s hearing was to determine if there is enough evidence for the case to go to trial.
The hearing follows more than a week of demonstrations across the US over the May 25 death in Minneapolis police custody of George Floyd, also a black American.
Four officers have been charged in that case.
Dial said he had evidence from social media and elsewhere that McMichael had used racial slurs in the past.
McMichael is a former US Coast Guard boarding officer.
Dial said the three defendants — Bryan, Travis McMichael and his father Gregory McMichael — chased Arbery in pickup trucks and sought to box him in as he was jogging in their neighbourhood.
Gregory McMichael, 64, and his son Travis, 34, are charged with murder and aggravated assault.
Bryan, a neighbour of the McMichaels’ who took the cellphone video, was charged with felony murder and attempting to illegally detain and confine.
Jason Sheffield, an attorney for Travis McMichael, pressed Dial on whether Bryan was promised leniency for possible co-operation with the prosecution when he cited the alleged racial slur.
Dial said he was unaware of any such offer.
The three defendants were not charged until more than two months after the shooting.
State police stepped in to investigate after the video was widely seen and Glynn County police took no action, and the GBI pressed charges.
Police have said Gregory McMichael saw Arbery running in his neighbourhood and believed he looked like a burglary suspect.
The elder McMichael called his son and the two armed themselves and gave chase in a pickup truck, police have said.
Dial said video and other evidence indicated that the first of three shots from Travis McMichael’s shotgun was to Arbery’s chest.
“You see the front of his shirt is saturated with blood,” Dial said. “The second shot is off camera as well but you do see the blood mist come into the camera screen.”
