Derek Chauvin is on trial for George Floyd's death

By Mike Hayes, Melissa Mahtani and Meg Wagner, CNN

Updated 12:06 AM ET, Fri April 16, 2021
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12:53 p.m. ET, April 15, 2021

Here's what happened on the last day of witness testimony in Chauvin's trial

Pool
Pool

A lot happened in the trial of ex-Minneapolis police officer Derek Chauvin today: The judge denied the prosecution's request to present "new evidence," both sides rested and the jury went into recess for a long weekend.

If you're just reading in now, here's how the morning unfolded:

  • Chauvin chose not to testify: At the start of court proceedings today, Chauvin said he would invoke his Fifth Amendment right and would not testify in his own defense.  Chauvin told the court he understood he had the option to testify, but will not. 
  • The prosecution's request was denied: Judge Peter Cahill rejected a prosecution request to present "new evidence" during a rebuttal case of “blood gas readings” regarding carbon monoxide levels found in George Floyd’s blood. The judge reached a compromise with the prosecution, saying they could discuss Floyd's oxygen levels instead — but said if prosecutors brought up the test results at all, a mistrial would be ruled.
  • The prosecutor's witness was on a "short leash" in rebuttal testimony: The prosecution called Dr. Martin Tobin, a pulmonologist, as a rebuttal witness to rebut the testimony of defense expert witness Dr. David Fowler, a retired forensic pathologist. During the testimony, Tobin said Fowler was "simply wrong" on Floyd’s carbon monoxide level. CNN legal analyst Laura Coates explained Tobin was "on the shortest, tightest leash possible" to ensure the judge did not declare a mistrial.
  • Both sides rested: Following the rebuttal testimony, both the defense and prosecution rested. Judge Cahill said closing arguments would begin on Monday, and adjourned the trial for a long weekend. The jury will be back at 10 a.m. ET Monday.
11:59 a.m. ET, April 15, 2021

Trial has adjourned until Monday morning

After a dramatic morning in the trial of Derek Chauvin, the prosecution and defense have rested. The jury returns on Monday at 10 a.m. ET.

11:59 a.m. ET, April 15, 2021

Defense and prosecution rest in the trial of Derek Chauvin

Pool
Pool

Following the rebuttal testimony from Dr. Martin Tobin, a pulmonologist, both the defense and prosecution rested.

Closing arguments are set for Monday.

11:57 a.m. ET, April 15, 2021

Pulmonologist cross-examined by the defense

Dr. Martin Tobin testifies on Thursday, April 15.
Dr. Martin Tobin testifies on Thursday, April 15. Pool

Dr. Martin Tobin, a pulmonologist, said during rebuttal testimony that the opinion of defense expert witness Dr. David Fowler regarding George Floyd's potential level of carbon monoxide in his blood was "simply wrong."

He was just cross-examined by the defense.

11:53 a.m. ET, April 15, 2021

CNN analyst: Jury was not present during conversation about new carbon monoxide test evidence 

From CNN's Laura Coates / Written by CNN's Maureen Chowdhury

The jury was not present during discussion about the prosecution potentially introducing new evidence about George Floyd's carbon monoxide blood levels, legal analyst Laura Coates explained. Judge Peter Cahill ruled that the prosecution cannot use this new evidence in their rebuttal case.

"That seed of reasonable doubt has not been planted," she said.

"Here's the thing. You and I and all of us are in the court of public opinion, not in the courtroom. That entire transaction just now, that exchange, did not take place in front of the jury. So the jury does not know that this has now happened. It is a good thing for the prosecution and also a good thing for the defense if they believe, that of course, this data that undermines their theory," Coates said.

The judge reached a compromise with the prosecution that they can discuss George Floyd's oxygen levels instead, but they cannot bring up the test results at all or a mistrial will be ruled.

"Judges don't want to give the prosecutors two bites at the apple. They don't want redundant testimony. If you could have raised it earlier, you should have, you had the chance, sit down. This time the prosecution is saying that when Dr. Fowler raised the issue of carbon monoxide poisoning, and although we had some semblance of what the theory might be, you presented some new theories, 'So, we're not asking for a second bite of the apple, Your Honor, we want a first bite of at the apple based on this new theory.' The problem is the prosecution made a mistake. They did not take seriously the thought of carbon monoxide poisoning as potentially being a viable claim to be raised by this doctor. They may have overlooked the data and did not present it through their own witnesses to rebut and preempt this," Coates continued.

11:56 a.m. ET, April 15, 2021

Pulmonologist says defense witness is "simply wrong" on Floyd’s carbon monoxide level

Dr. Martin Tobin, left, testifies on Thursday, April 15. Dr. David Fowler, right, testifies on April 14.
Dr. Martin Tobin, left, testifies on Thursday, April 15. Dr. David Fowler, right, testifies on April 14. Pool

Dr. Martin Tobin, a pulmonologist, said during rebuttal testimony that the opinion of defense expert witness Dr. David Fowler regarding George Floyd's potential level of carbon monoxide in his blood was "simply wrong."

Tobin said medical records showed Floyd's oxygen saturation was 98% when he died. Prosecutor Jerry Blackwell asked him: "Does that tell us anything whatsoever about what the carbon monoxide content could have been at a maximum?" 

Tobin said: "Yes, it does. It tells us that if hemoglobin is saturated at 98%, it has – for others is 2%. So the maximum amount of carbon monoxide would be 2%." 

Why this is important: Dr. Fowler testified that it was possible that carbon monoxide ingestion could have been one of the causes of Floyd's death. He based this on observations of Floyd being pinned on the ground near the tailpipe of the police cruiser that officers were trying to get him into. Fowler acknowledged that he had not seen any data on Floyd's carbon monoxide levels prior to testifying.

During his testimony Fowler said that it was his opinion that Floyd's carbon monoxide levels in his blood could have increased by 10% to 15%. Tobin said that assessment is "simply wrong."

Watch:

11:44 a.m. ET, April 15, 2021

Dr. Tobin has to be "on the shortest, tightest leash possible" to prevent a mistrial, CNN analyst says

From CNN's Aditi Sangal

As the prosecution recalled Dr. Martin Tobin as a rebuttal witness at the Chauvin trial, CNN legal analyst Laura Coates says the pulmonologist will have to be on the "on the shortest, tightest leash possible" to ensure the judge does not declare a mistrial.

Tobin previously testified that it was his opinion that George Floyd died from low oxygen levels, and he will now be rebutting the testimony of defense expert witness Dr. David Fowler, a retired forensic pathologist.

"The judge has been very clear he will declare a mistrial because any hint, any suggestion or mention of the Hennepin County data will be prejudicial to a defendant who gave notice through their witness expert about a theory of carbon monoxide poisoning. And they did not have the data disclosed to them in time to be able to potentially fully flush it out or to recoil on their own theory," Coates explained.

She added:

"Appellate courts have no tolerance for prosecutors who do not disclose information in a timely fashion and try to get it through a rebuttal witness. And so, this prosecution team is going to have to be extraordinarily prudent. And I hope that this witness, as informative as he is, can stay ton that leash."

The risk is that witnesses can be like wild cards, just like jurors, Coates explained.

"I don't care if you are the most seasoned expert testifying witness. Sometimes they do not understand the implications of their slip-ups or making a statement ... Defense attorneys are always on guard with this very point," she said. "In the event of a conviction, they want to have their ducks in a row of how they can seek an appeal to overturn based on, especially, prosecutorial misconduct or any allegations based on that."

11:27 a.m. ET, April 15, 2021

The prosecution recalls pulmonologist as a rebuttal witness

Dr. Martin Tobin testifies on Thursday, April 15.
Dr. Martin Tobin testifies on Thursday, April 15. Pool

The prosecution has called Dr. Martin Tobin, a pulmonologist, as a rebuttal witness at the Chauvin trial.

Tobin is rebutting the testimony of defense expert witness Dr. David Fowler, a retired forensic pathologist.

Tobin previously testified that it was his opinion that George Floyd died from low oxygen levels.

11:24 a.m. ET, April 15, 2021

The defense rests its case

Pool
Pool

Defense attorney Eric Nelson just rested the defense's case in the Derek Chauvin murder trial.

Prior to that, Chauvin declared in court that he would invoke his Fifth Amendment privilege and not testify.

What happens next: The prosecution is expected to call one rebuttal witness today.