A witness in a Minneapolis murder trial involving Derek Chauvin compared the former police officer's hold on George Floyd to a martial art "kill choke" move.

Donald Williams, 33, said he has been a mixed martial arts fighter since 2003 and recognized the move done by Derek Chauvin on many occasions while he pressed his knee against Floyd's neck.

Williams was the third witness called by state prosecutors in the case and said that the knee was diagonal across the throat.

"The officer on top was shimmying to actually get the final choke in while he was on top, the kill choke," Williams told Minnesota Assistant Attorney General Matthew Frank during the direct examination as New York Post reported.

Williams said that Derek Chauvin only looked up when he told the former cop that it was a blood choke.

"We looked at each other dead in the eye," he noted. Williams yelled at Chauvin to check for a pulse as he knelt on George Floyd for over nine minutes in May.

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Opening Statements on Derek Chauvin's Trial

Chauvin's lawyer claimed that unruly bystanders had distracted Minnesota police officers while the former cop kept his knee on Floyd's neck for an extended period of time.

Lead defense attorney Eric Nelson suggested that the screaming crowd were somehow to blame for the serious events that ended with George Floyd's death.

The defense attorney said that Derek Chauvin acted within the scope of his job and that he acted appropriately, as he surveyed potential threats from a growing group of an enraged bystanders, according to a Crime Online report.

Nelson noted that there was a growing crowd and what officers perceived to be a threat, adding that they "are called names."

Hennepin County's autopsy report stated that there was no evidence to support the claims of traumatic asphyxia or strangulation.

However, an independent autopsy showed that sustained forceful pressuring against George Floyd's neck and back led to his death.

Both of the said autopsy reports mentioned drugs in George Floyd's system but concluded that the death was a homicide.

Derek Chauvin is charged with third-degree murder, second-degree unintentional murder, and second-degree manslaughter charges connected with George Floyd's death.

Aside from Chauvin, three other former police officers were also charged, namely Thomas Lane, 37, J. Alexander Kueng, 26, and Tou Thao, 34.

They were all charged with aiding and abetting second-degree murder and aiding and abetting second-degree manslaughter.

If convicted for second-degree murder, Chauvin could face up to 40 years imprisonment and 25 years for third-degree murder, Daily Mail reported. If found guilty of manslaughter, the former police officer could face a maximum penalty of 10 years. 

Reverend Al Sharpton, Floyd family attorney Benjamin Crump, Floyd's nephew Brandon Williams and other supporters were in the silent act of protest.

Nelson maintained that George Floyd died not because of Chauvin but because of Floyd's own making, such as his hypertension, ingestion of opioids, and the adrenaline in his system as he struggled with the officers.

Nelson noted that when the public hears the law and applies reasons, the verdict would be Derek Chauvin not guilty.

READ MORE: Court Thinking to Reinstate Third-Degree Murder Charge vs. Derek Chauvin 

WATCH: Derek Chauvin Trial Begins With Opening Statements and First Witnesses - From Washington Post