Sgt. Ker Yang, the Minneapolis police official in charge of crisis-intervention training, and use-of-force instructor Lt. Johnny Mercil became the latest department members to testify as part of an effort by prosecutors to demolish the argument that Chauvin was doing what he was trained to do when he put his knee on George Floyd's neck last May.

Mr Chauvin, 45, was filmed kneeling on Mr Floyd for over nine minutes during Mr Floyd's arrest last May. A bystander recorded Chauvin with his knee on Floyd's neck for more than nine minutes, and Floyd is heard in the video saying he can not breathe.

George Floyd's death sparked a global movement of protest and desire for change. Video captured by a bystander showed the handcuffed Floyd repeatedly say he couldn't breathe. Mercil said those who attended were taught that the sanctity of life is a cornerstone of departmental policy and that officers must use the least amount of force required to get a suspect to comply.

Yang said officers are taught to make critical decisions in dealing with people in crisis, including those suffering mental problems or the effects of drug use, and then de-escalate the situation.

In June, he called Floyd's death a "murder" in response to an inquiry from the Minneapolis Star Tribune.

Steve Schleicher, one of prosecuting attorneys, showed Lieutenant Johnny Mercil, who teaches the proper use of force for the department, a photograph of Chauvin kneeling on Floyd's neck and asked if he was using an authorized neck restraint under the circumstances.

During that time, Morries Lester Hall, a key witness who was with George Floyd on the day he died, will appear remotely from the Hennepin County jail. Stiger said when Floyd was resisting efforts to get him into a squad vehicle, officers were justified in using force, but once he was on the ground and no longer resisting, officers "should have slowed down or stopped their force as well". He said he later tried for another 30 minutes.

"My opinion was that the force was excessive", he said.

Chauvin's lawyers argue Floyd's death was a drug overdose, though prosecutors have said medical evidence would contradict that.

Chauvin's lawyer, Eric Nelson, has argued that Chauvin "did exactly what he had been trained to do over his 19-year career" and that it was Floyd's use of illegal drugs and his underlying health conditions - not the officer's knee - that killed him.

Nelson told Cahill he planned to ask Hall whether he gave Floyd any controlled substances and why Hall left Minnesota immediately after the incident.

The county medical examiner has ruled Floyd's death a homicide at the hands of the police, and noted Floyd had also taken fentanyl and methamphetamine before his death.

Mercil testified that a neck restraint created to render a suspect unconscious is authorised only when the suspect is actively and aggressively resisting.

Arradondo, the city's first Black chief, fired Chauvin and three other officers the day after Floyd's death.

Prosecutor Steve Schleicher noted that while some people may become more risky under the influence of drugs or alcohol, some may actually be "more vulnerable".

"I vehemently disagree that that was appropriate use of force for that situation on May 25", Arradondo testified on Monday. A panicky-sounding Floyd writhed and claimed to be claustrophobic as police tried to put him in the squad auto.

Officers kept restraining Floyd - with Chauvin kneeling on his neck, another kneeling on Floyd's back and a third holding his feet - until the ambulance got there, even after he became unresponsive, according to testimony and video footage.