A leading use of force expert with one of the nation's largest urban police departments testified Tuesday in Derek Chauvin's murder trial that the evidence from George Floyd's arrest late last spring showed him there were numerous clear signs that the now-fired Minneapolis officer should have eased up on his use of force.

Los Angeles Police Sgt. Jody Stiger's conclusions followed testimony earlier Tuesday from two Minneapolis police officers with experience in crisis intervention and use of force about proper procedures during the seventh day of testimony in Hennepin County District Court, with one of them saying that Chauvin's knee on Floyd's neck was not part of department training.

Stiger, a member of a police force with roughly 9,000 sworn officers, was hired by the prosecution to review relevant video from the scene, court records and training and policy material in preparation for his testimony.

Asked to sum up his analysis of what he learned about Floyd's arrest, Stiger said, "My opinion is that the force was excessive."

"Initially, when Mr. Floyd was being placed in the back seat of the vehicle, the officers were justified in trying to have him comply and sit in the back seat of the vehicle," the sergeant said. "However, once he was placed in the prone position on the ground, he slowly ceased his resistance and the officers — or ex-officers, I should say — should have slowed down or stopped their force."

Besides Floyd backing off his resistance, Stiger said other factors the officers should have considered when weighing use of force includes the nature of the original alleged offense, in Floyd's case the passing of a counterfeit $20 bill at Cup Foods at 38th and Chicago on May 25.

"Typically, in a normal situation" for what the sergeant said called low-level offense, "you wouldn't expect to use any force."

Stiger also said he could hear on one of the videos Floyd say "thank you" to the officers once they got him out of the squad and on his knees while still handcuffed behind his back.

From there, Floyd can be seen being placed on his chest in the prone position. Stiger noted that he saw Floyd one time "kicked their arms in an attempt to possibly break free from the officers' grasp."

Chauvin then asked for what is known as a "hobble," a nylon strap that connects a suspect's ankles and waistline in order to prevent kicking.

However, after that one kick, police changed their mind and did not put the hobble on Floyd.

Stiger explained that decision to reverse course: "Based on my review, I would believe that he was starting to comply, and his aggression was starting to cease."

Prosecutor Steve Schleicher than asked whether the compliance continued, and Stiger said it did throughout the more than nine minutes that Floyd remained pinned on the pavement by Chauvin until paramedics arrived.

Tuesday ended with Stiger still on the stand and with the defense yet to cross examine the prosecution's hired witness.

At the day's start, Minneapolis Police Sgt. Ker Yang, who serves as the department's crisis intervention training coordinator, and Lt. Johnny Mercil, who oversees MPD's use of force training, became the seventh and eighth current or former Minneapolis police officers to testify. That included Chief Medaria Arradondo.

Yang testified that in his job he coordinates with civilian mental health professionals to train officers who encounter people in crisis situations, such as mental health issues. Although Yang was never directly asked about Chauvin's actions, he discussed the best practices in dealing with people in crisis, or a situation "beyond a person's coping mechanism. What it is beyond their control, they don't know what to do." That could also include people under the influence of drugs and alcohol or suffering from anxiety.

Yang said he trains officers to "bring them back down."

"When it is safe and feasible, we shall de-escalate," Yang said, adding that the model for crisis intervention focuses on voice, neutrality, respect and trust. "It is useful, and it is practical."

He was followed by Mercil, who explained to the jury when two specific neck restraints are allowed on a subject: whether it is one that renders a suspect unconscious to counter "active aggression" or one that keeps someone conscious while offering the lesser "active resistance."

He testified about "red zones," where injury tends to range from serious to long lasting and could include serious bodily injury or death. Areas included the head, neck and sternum, among others.

Mercil was shown a photo from the viral bystander video of Floyd under Chauvin's knee and then asked whether that tactic is part of department training that Chauvin and all other officers have received.

"No, sir," the lieutenant said. At the same time, he acknowledged that department policy does not explicitly forbid such an act, but he added that this position should stop once a suspect is handcuffed and under control, as Floyd was that night.

During cross examination, defense attorney Eric Nelson offered for the first time a series of photographs from Officer Thomas Lane's body camera. Mercil agreed they show Chauvin's knee and shin on Floyd's shoulder area. The images offer four moments within a five-minute span.

After viewing those photos, Nelson asked Mercil, "Does this appear to be a neck restraint?" He responded with "no."

Nelson also raised with questions of a general nature about whether suspects Mercil has ever arrested "at times are making excuses," say they are suffering a medical emergency of declare " 'I can't breathe' " to avoid going to jail. The lieutenant said he's had those experiences.

While pinned on the pavement, Floyd was asked by police during his arrest how he can talk while at the same time be unable to breathe, a question that appeared to raise the question among the officers about Floyd being deceptive.

The afternoon started with testimony from Nicole Mackenzie, the department's medical support coordinator and first aid educator of officers.

Mackenzie helped the prosecution make two points: that cardiopulmonary resuscitation (CPR) can be started while waiting for paramedics to arrive and that talking doesn't contradict someone's contention that they can't breathe.

Prosecutor Schleicher asked Mackenzie whether officers are trained to go ahead with CPR before an ambulance arrives. She said yes. Floyd did not receive medical attention while under arrest until two paramedics arrived.

In the context of talking during an "I can't breathe" plea, Mackenzie said: "There is a possibility somebody could be in respiratory distress and still be able to verbalize it. Just because they're speaking doesn't mean they're breathing adequately."

Mackenzie acknowledged under questioning from Nelson that police officers should ensure that a scene is safe before rendering aid. This is a theme the defense attorney has visited numerous times since his opening statement at the start of last week.

Nelson also asked whether agonal breathing — or involuntary gasps sometimes made by people under cardiac arrest — could be confused as regular breathing. She confirmed that as well.

Mackenzie also agreed that chaotic scenes can contribute to a first responder's ability to provide aid.

"If you're trying to be heads down on a patient that you need to render aid to, it's very difficult to focus on that patient while there's other things around you," she said, "if you don't feel safe around you, if you don't have enough resources, it's very difficult to focus on the one thing in front of you."

Nelson asked: "Does it make it more likely that you may miss signs that a patient is experiencing something?"

"Yes," Mackenzie replied.

"The distraction can harm the potential care of the patient?" Nelson inquired.

"Yes," Mackenzie said.

Schleicher came back and asked whether a crowd of agitated onlookers excuses a police officer from rendering aid.

"Only if they were physically getting themselves involved," Mackenzie said. At the scene of the arrest, some bystanders grew increasingly louder in their pleadings with the officers and sometimes used profanity, but never physically threatened Chauvin or the other officers on Floyd's body, according to any of the witnesses or video evidence presented so far.

Before the day's testimony began, attorneys made their arguments Tuesday about whether a witness to Floyd's arrest should be compelled to testify.

Morries L. Hall was with Floyd on that night late last spring, when Floyd was apprehended by police outside the corner store and pinned on the pavement under an officer's knee until dying.

Hall has said he would invoke his Fifth Amendment constitutional right against self-incrimination and not testify as ordered in the fired police officer's trial in Hennepin County District Court.

Judge Peter Cahill listened on Tuesday to points raised by Hall's attorney, Adrienne Cousins, and from the defense and prosecution before putting off any ruling on the issue until at least late in the week.

In the hearing out of the view of the jury, Hall appeared via video hookup and explained through his attorney that he would be exposed to a potential third-degree murder charge and other possible felony counts should he be forced to answer questions in Chauvin's trial.

Cousins said her client "has been provided no immunity, no protection for his testimony whatsoever. I cannot envision any topics Mr. Hall would be called to testify on that would be relevant to the case that would not incriminate him."

Hall is listed by both the defense and the prosecution as a possible witness as they present their respective cases.

Defense attorney Nelson disclosed the areas of questions he has for Hall. They include inquiries about: what Floyd and Hall were doing together that day, Hall possibly passing Floyd a counterfeit bill in the store, providing Floyd with drugs and other questions about illicit drug use.

"Going for the ignition when police arrived ... taking something out of his backpack and throwing it," giving false names to police and his decision to leave Minnesota for Texas immediately after Floyd's death, Nelson continued.

Testimony last week from Floyd's girlfriend revealed her belief that Hall provided drugs to Floyd earlier in the month of his death.

Cahill agreed that all those topics would expose Hall to self-incrimination while testifying. The judge said he did see that Hall could talk about being in the SUV with Floyd and share his observations of his friend, but his attorney and prosecutor Matthew Frank disagreed.

Again, Cousins said, that too could incriminate her client.

Frank concurred with Cousins, saying that limiting the line of questioning "creates a huge problem" in that Hall would be invoking his Fifth Amendment right in front of the jury when asked follow-up questions.

"It won't exist in a vacuum, there will be other questioning, and we will have the right to question him about his credibility and other aspects of that interaction that would lead, unfortunately and potentially, to him invoking question by question in front of the jury."

Ultimately, Cahill directed Nelson to put in writing the questions he would ask Hall and bring those back by Thursday for further discussion.

Chauvin is charged with second-degree unintentional murder, third-degree murder and second-degree manslaughter in the killing of Floyd. Three other fired officers who assisted in Floyd's 2020 arrest — J. Alexander Kueng, Lane and Tou Thao — are scheduled to be tried in August on charges of aiding and abetting murder and manslaughter.

Paul Walsh • 612-673-4482