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Minneapolis Police Chief Medaria Arradondo took the stand on Monday in the ongoing trial of former officer Derek Chauvin, who has been accused of murder and manslaughter in the May 2020 death of George Floyd

Arradondo, the city's first Black chief, fired Chauvin and three other officers the day after Floyd's May 25 death. In June, he called it "murder" in response to an inquiry from the Star Tribune. 

On Monday, he testified about Minneapolis Police Department (MPD) policy that dictates that officers must use tactics to de-escalate a situation whenever reasonable to do so, in an effort to avoid or minimize the use of force.

This Feb. 17, 2021, file photo shows Minneapolis Police Chief Medaria Arradondo addressing the media on preparations for the upcoming Derek Chauvin trial in Minneapolis.  (Richard Tsong-Taatarii/Star Tribune via AP)

Chauvin, 45, faces charges of second- and third-degree murder and manslaughter. He is accused of holding his knee against Floyd's neck for 9 minutes and 29 seconds, even though Floyd, 46, was handcuffed, lying in the prone position and saying he could not breathe. 

Three other officers – J. Kueng, Tou Thao and Thomas Lane – have also been charged in connection with Floyd's death and are expecting to stand trial later this year. 

Arradondo testified on Monday not only that Chauvin, a 19-year veteran of the force, should have let Floyd up sooner, but that the pressure on Floyd’s neck did not appear to be light to moderate, as called for under the department's neck-restraint policy. He also said Chauvin failed in his duty to render first aid before the ambulance arrived, and that he violated policy requiring officers to de-escalate tense situations if they can to avoid or minimize the use of force.

"That action is not de-escalation," the police chief said. "And when we talk about the framework of our sanctity of life and when we talk about our principles and the values that we have, that action goes contrary to what we are talking about."

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When prompted on Monday, Arradondo read bullet points from MPD’s Professional Policing Policy, including one that read: "Ensure that the length of any detention is no longer than necessary to take appropriate action for the known or suspected offense."

Prosecutor Steve Schleicher noted that while some people may become more dangerous under the influence of drugs or alcohol, some may actually be "more vulnerable." Arradondo agreed and acknowledged that this must also be taken into consideration when officers decide to use force.

"It’s recognizing that when we get the call from our communities, it may not often be their best day, and they may be experiencing something that’s very traumatic," the chief said.

Before he was pinned to the ground, a handcuffed and frantic Floyd struggled with police who were trying to put him in a squad car, saying he was claustrophobic.

In response to questions and a data request from the Star Tribune, Arradondo issued a statement in June saying: "Mr. George Floyd’s tragic death was not due to a lack of training – the training was there. Chauvin knew what he was doing."

Arradondo went on to say: "The officers knew what was happening – one intentionally caused it and the others failed to prevent it. This was murder – it wasn’t a lack of training."

In this image from video, witness Minneapolis Police Chief Medaria Arradondo testifies as Hennepin County Judge Peter Cahill presides Monday, April 5, 2021, in the trial of former Minneapolis police Officer Derek Chauvin at the Hennepin County Courthouse in Minneapolis. Chauvin is charged in the May 25, 2020 death of George Floyd. (Court TV via AP, Pool)

Arradondo said in his statement at the time that both Chauvin and Thao took training on the dangers of positional asphyxiation in 2014. The training, which covered how to get an arrestee from a prone position into a recovery or seated position, was required after a 2013 settlement with the family of David Cornelius Smith, a handcuffed Black man who died in 2010 after police pinned him face down.

He said the department also changed its policy in June 2014 to explicitly require moving an arrestee from a prone position to a recovery position when the highest degree of restraint is used, and to require continuous monitoring of the person’s condition.

He also said trainees continue to discuss the risks of in-custody deaths, and there’s "simply no way that any competent officer" would be unaware of the need to move an arrestee so he or she can breathe freely.

The defense has argued that Chauvin did what he was trained to do and that Floyd's use of illegal drugs and his underlying health conditions caused his death.

During cross-examination, Chauvin attorney Eric Nelson asked Arradondo about his knowledge of physics in an apparent attempt to bring into question his ability to accurately say how much pressure Chauvin had actually been applying to Floyd's neck.

Nelson also asked the police chief when he had last worked on the streets making arrests. The chief says acknowledged it has been "many years."

Nelson also emphasized that the amount of force used should vary on a "situation-by-situation basis."

He later raised the question about "camera-perspective bias," with which Arradondo said he was not familiar.

Nelson played for Arradondo bystander video from the crime scene, which showed Chauvin's knee on Floyd's body, and then played a second video from a different angle in the same moments before and while Floyd was being placed on a gurney.

The defense attorney then showed both camera views simultaneously and asked: "From the perspective of [bystander] Ms. [Darnella] Frazier’s camera, it would appear that Officer Chauvin’s knee is on the neck of Mr. Floyd."

Arradondo said yes. Then, Nelson referenced the second video, showing the officer's body camera footage, and asked: "Would you agree that from the perspective of Officer Kueng's body camera that it appears that Officer Chauvin’s knee was more on Mr. Floyd’s shoulder blade?"

"Yes," Arradondo conceded.

Schleicher, on behalf of the prosecution, then immediately followed up with Arradondo's response to Nelsons questions about "camera-perspective bias."

Schleicher asked the police chief if he believed Floyd to be "actively resisting," during the short clip he had just been shown. When Arradondo said no, Schleicher asked if Arradondo believed Floyd was "passively resisting" in those moments seen in the video.

Arradondo responded: "No, as a matter of fact, as I saw that video, I didn't even know if Mr. Floyd was alive at that time."

Earlier on Monday, the emergency room doctor who pronounced Floyd dead after trying to resuscitate him testified Monday that he theorized at the time that Floyd's heart most likely stopped because he didn't get enough oxygen.

Dr. Bradford Langenfeld, who was a senior resident on duty that night at Hennepin County Medical Center, took the stand at the beginning of Week Two of former Minneapolis Officer Derek Chauvin’s murder trial, as prosecutors sought to establish that it was Chauvin’s knee on the Black man’s neck that killed him.

Langenfeld said Floyd’s heart had stopped by the time he arrived at the hospital. The doctor said he was not told of any efforts at the scene by bystanders or police to resuscitate Floyd but that paramedics told him they had tried for about 30 minutes.

Under questioning by prosecutor Jerry Blackwell, Langenfeld said that based on the information he had, it was "more likely than the other possibilities" that Floyd's cardiac arrest – the stopping of his heart – was caused by asphyxia, or insufficient oxygen. 

Langenfeld said "any amount of time" a patient spends in cardiac arrest without immediate CPR decreases the chance of a good outcome. He said there is an approximately 10% to 15% decrease in survival for every minute that CPR is not administered.

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Chauvin attorney Eric Nelson questioned Langenfeld about whether some drugs can cause hypoxia, or insufficient oxygen. The doctor acknowledged that fentanyl and methamphetamine, both of which were found in Floyd's body, can do so.

The county medical examiner's office ultimately classified Floyd's death a homicide – that is, a death at the hands of someone else.

The full report said Floyd died of "cardiopulmonary arrest, complicating law enforcement subdual, restraint, and neck compression." A summary report listed fentanyl intoxication and recent methamphetamine use under "other significant conditions" but not under "cause of death."

Under cross-examination from Nelson, Langenfeld said Floyd’s carbon dioxide levels were more than twice as high as levels in a healthy person, and he agreed that could be attributed to a respiratory problem. But on questioning from the prosecutor, the doctor said the high levels were also consistent with cardiac arrest.

Fox News' Danielle Wallace contributed to this report, as well as the Associated Press.