MINNEAPOLIS (NewsNation Now) — An expert in the use of force by police on Wednesday faulted the actions of former Minneapolis policeman Derek Chauvin in last year’s deadly arrest of George Floyd, testifying that no force should have been used after Floyd was handcuffed and prone.

Los Angeles Police Department Sergeant Jody Stiger appeared as a prosecution witness at Chauvin’s murder trial, as prosecutors sought to further demonstrate that the fired former officer disregarded his training when he knelt on Floyd’s neck for more than nine minutes.

Stiger told jurors that Floyd did not pose an immediate threat or actively resisted arrest at the time when Chauvin used deadly force on the 46-year-old Black man while he was handcuffed in the prone position in the May 2020 incident outside a neighborhood market after being accused of trying to pass a counterfeit $20 bill.

“My opinion was that no force was reasonable in that position,” Stiger testified. “The pressure caused by the body weight could cause positional asphyxia and could cause death.”

Chauvin had his knee on George Floyd’s neck — and was bearing down with most of his weight — the entire 9 1/2 minutes as he was facedown on the ground with his hands cuffed behind his back, Stiger said, concluding Chauvin knelt on Floyd’s neck or neck area until paramedics arrived.

Stiger, who has reviewed 2,500 cases in which police used force, resumed his testimony after first appearing on Tuesday.

Prosecutor Steve Schleicher asked Stiger to describe several photographs showing officers restraining Floyd. Stiger testified that it appeared Chauvin’s use of force was excessive.

“He was handcuffed, not attempting to resist, not attempting to assaulted officers, kick, punch of that nature,” Stiger said of Floyd.

Stiger also testified that Chauvin squeezed Floyd’s hand to get him to comply with the officer’s orders while he was handcuffed in the prone position. Stiger testified that Floyd did not appear to have an opportunity to comply.

“At that point it was just pain,” Stiger said.

Asked by prosecutors whether Chauvin had an obligation to take Floyd’s distress into account as he was considering what level of force to use, Stiger replied: “Absolutely. As as the time went on, clearly in the video, you could see that Mr. Floyd’s … health was deteriorating. His breath was getting lower. His tone of voice was getting lower. His movements were starting to cease.”

“So at that point, as an officer on scene, you have a responsibility to realize that, ‘OK, something is not right,’” Stiger continued. “‘Something has changed drastically from what was occurring earlier.’ So therefore you have a responsibility to take some type of action.”

Records showed Chauvin completed 867 hours of police training. Stiger said that was “absolutely” enough time to prepare him for this situation.

Chauvin, who is white, has pleaded not guilty to murder and manslaughter charges, arguing that he was following the training he had received in his 19 years on the police force. Three other officers on the scene have been charged with aiding and abetting murder and will stand trial later this year.

In his cross-examination, Chauvin attorney Eric Nelson, asked how a reasonable officer would be trained to view a crowd while dealing with a suspect, “and somebody else is now pacing around and watching you and watching you and calling you names and saying (expletives).” Nelson said “this could be viewed by a reasonable officer as a threat.”

“As a potential threat, correct,” Stiger said.

The defense attorney also asked Stiger whether video showed Floyd picked up his head and moved it at times.

“Slightly, yes. He attempted to,” Stiger replied.

Chauvin’s lawyer also noted that dispatchers had described Floyd as between 6 feet and 6-foot-6 and possibly under the influence. Stiger agreed it was reasonable for Chauvin to come to the scene with a heightened sense of awareness.

Nelson suggested that when Chauvin told Floyd to “relax,” he was trying to calm him down and reassure him. And Nelson said that given typical EMS response times, it was reasonable for Chauvin to believe that paramedics would be there soon.

Nelson has argued that the now-fired white officer “did exactly what he had been trained to do over his 19-year career,” and he has suggested that the illegal drugs in Floyd’s system and his underlying health conditions are what killed him, not Chauvin’s knee.

Nelson seized on the drug angle in cross-examining Stiger, playing a snippet of then-Officer J. Kueng’s body-camera video and asking whether Stiger could hear Floyd say, “I ate too many drugs.”

Stiger replied that he could not make out those words in the footage.

The Associated Press and Reuters contributed to this report. Reporting by Jonathan Allen and Brendan O’Brien of Reuters. Reporting by Amy Forliti, Steve Karnowski and Tammy Webber of AP.