Minneapolis, Minnesota – On the opening day of Derek Chauvin's trial, the jury was introduced to Donald Williams, the former MMA fighter who was heard and seen on video begging police officers to check the pulse of a dying George Floyd.

It was a chilling several minutes as the court listened to Donald Williams (33) recount the moments leading up to the death of George Floyd, allegedly at the knee of Minneapolis police officer Derek Chauvin.

As a former mixed martial arts practitioner, Williams has a wealth of knowledge about grappling moves and tactics, including various chokeholds, like the blood choke.

This is a type of hold that attacks one side of the neck, cuts off the circulation of the arteries, and stops blood flow throughout the head until the person is unconscious.

In his testimony streamed by ABC News, Williams identified the chokehold that Floyd was being held under by officer Chauvin as that type of restraint, noting also his belief that malicious intent was involved.

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He added that the only time Chauvin made eye contact with him throughout his pleading was directly after Williams called him out for administering a blood choke.

As Chauvin continued kneeling on Floyd's neck even despite the pleas and screams of bystanders, Williams observed the tragic final moments of the 46-year-old.

In what is only the beginning of very jarring and vivid testimony, he described Floyd's appearance as he was losing consciousness: "You see his eyes slowly, you know, pale out," he continued. "His eyes slowly rolled to the back of his head. You see blood coming out of his nose".

It was around this time in the testimony that the video feed from the courtroom cut out for unclear reasons.

Testimony will pick back up with Williams on Tuesday morning.