Minneapolis (AFP) - Police and medical experts delivered withering testimony against Derek Chauvin in the second week of trial for the white former Minneapolis police officer charged with killing George Floyd by kneeling on the Black man's neck for more than nine minutes.

Chauvin listened impassively as the experts testified that he used inappropriate "deadly force" in subduing the handcuffed 46-year-old, in violation of police procedures.

Police chief Medaria Arradondo

The chief of Minneapolis police said Monday that his former subordinate had violated the department's training and its "values" in kneeling on a "prone, handcuffed individual."

Kneeling on Floyd's neck could have been reasonable during the "first few seconds" of his May 25, 2020 arrest but it should have ended quickly, he said.

"Once Mr. Floyd had stopped resisting, and certainly once he was in distress and trying to verbalize that, that should have stopped," said Arradondo, 54, the first Black police chief in Minneapolis.

"That in no way, shape or form is anything that is by policy," he said. "It is not part of our training and it is certainly not part of our ethics or our values."

Jody Stiger, use-of-force specialist

A Los Angeles police officer who is a use-of-force specialist, Stiger said Wednesday that Chauvin's actions were "deadly force" because Floyd was prone, handcuffed and not resisting.

"An officer is only allowed to use a level of force that is proportional to the seriousness of the crime, or the level of resistance," he said.

Floyd had been accused of passing a counterfeit $20 bill in a nearby store.

Stiger acknowledged that Floyd was initially resisting arrest, but that once he was subdued on the ground "my opinion was no force should have been used once he was in that position."

Police practice for the past 20 years has been to put handcuffed suspects on their side or in a seated position, he testified.

Martin Tobin, respiratory doctor

The pulmonologist detailed the final moments of Floyd's life on Thursday.

Floyd died from "a low level of oxygen," Tobin told the nine-woman, five-man jury, providing commentary as a graphic video of what he said was the moment of Floyd's death was shown to the panel.

"You can see his eyes, he's conscious, and then you see that he isn't," he said. "One second he's alive and one second he is no longer.

"That's the moment the life goes out of his body."

The low oxygen "caused damage to his brain," Tobin said, and arrhythmia -- an irregular heartbeat -- which "caused his heart to stop."

Tobin dismissed defense claims that pre-existing medical conditions may have contributed to Floyd's death, along with the impact of illegal drugs methamphetamine and fentanyl.

"A healthy person subjected to what Mr. Floyd was subjected to would have died," he said.

Baker, the chief medical examiner for Minnesota's Hennepin County who conducted the autopsy on Floyd, told the jury that the cause of death was "restraint and neck compression" while being subdued by police.

He noted that Floyd -- who had heart disease -- had scuffled with the officers arresting him before being handcuffed and placed face down on the ground.

"Those events are going to cause stress hormones to pour out into your body, specifically things like adrenaline," he said.

"And what that adrenaline is going to do is it's going to ask your heart to beat faster.

"It's going to ask your body for more oxygen so that you can get through that altercation," he said. "And in my opinion, the law enforcement subdual, restraint and the neck compression was just more than Mr. Floyd could take by virtue of those heart conditions."

He denied an assertion by Chauvin's lawyer that Floyd's heart disease and drug use should be blamed for his death.