A man who was among the onlookers shouting at a Minneapolis police officer to get off George Floyd last May has testified that he dialled police after paramedics took Mr Floyd away "because I believed I witnessed a murder".
Donald Williams, a former wrestler who said he was trained in mixed martial arts including chokeholds, returned to the witness stand on Tuesday, a day after describing seeing Mr Floyd struggle for air and his eyes roll back into his head.
He said he watched Mr Floyd "slowly fade away... like a fish in a bag".
Prosecutor Matthew Frank played back Mr Williams' 911 call, on which he is heard identifying officer Derek Chauvin by his badge number and telling the dispatcher that Mr Chauvin had been keeping his knee on Mr Floyd's neck despite warnings that Mr Floyd's life was in danger.
She offers to switch him to a sergeant.
As he is being switched, Mr Williams can he heard yelling at the officers, "Y'all is murderers, bro!"
On Monday, Mr Williams said he thought Mr Chauvin used a shimmying motion several times to increase the pressure on Mr Floyd.
He said he yelled to the officer that he was cutting off Mr Floyd's blood supply.
Mr Williams recalled that Mr Floyd's voice grew thicker as his breathing became more laboured and he eventually stopped moving.
During cross-examination on Tuesday, Mr Chauvin's lawyer Eric Nelson sought to show that Mr Chauvin and his fellow officers found themselves in an increasingly tense and distracting situation, with the crowd of onlookers getting agitated over Mr Floyd's treatment.
Mr Nelson pointed out that Mr Williams seemed to grow increasingly angry at police on the scene, swearing at and taunting Mr Chauvin with "tough guy," "bum" and other names, then calling Mr Chauvin expletives, which the defence lawyer repeated in court.
Mr Williams initially admitted he was getting angrier but then backtracked and said he was controlled and professional and was pleading for Mr Floyd's life but wasn't being heard.
Brandon Williams wears a mask and pendant with the image of his uncle, George Floyd, and raises his fist at the courthouse in Minneapolis, Minnesota. Source: AAP
Mr Williams said he was stepping on and off the curb, and at one point, Officer Tou Thao, who was controlling the crowd, put his hand on Mr Williams' chest.
Mr Williams admitted under questioning that he told Mr Thao he would beat the officers if Mr Thao touched him again.
Mr Williams was among the first witnesses as Mr Chauvin, 45, went on trial on charges of murder and manslaughter in Mr Floyd's death.
The death of the black man after he was held down by the white officer touched off sometimes-violent protests around the world and a reckoning over racism and police brutality.
Prosecutors led off their case by playing part of the harrowing bystander video of Mr Floyd's arrest.
Mr Chauvin and three other officers were fired soon after the footage became public.
Prosecutor Jerry Blackwell showed the jurors the video after telling them that the number to remember was 9 minutes, 29 seconds, the amount of time Mr Chauvin had Mr Floyd pinned to the pavement "until the very life was squeezed out of him".
Mr Nelson countered by arguing: "Derek Chauvin did exactly what he had been trained to do over his 19-year career."
The defence lawyer also disputed that Mr Chauvin was to blame for Mr Floyd's death, as prosecutors contend.
Mr Floyd, 46, had none of the telltale signs of asphyxiation and had fentanyl and methamphetamine in his system, Mr Nelson said.
He said Mr Floyd's drug use, combined with his heart disease, high blood pressure and the adrenaline flowing through his body caused a heart rhythm disturbance that killed him.
"The evidence is far greater than 9 minutes and 29 seconds," Mr Nelson said.
