Testimony in the murder trial of former Minneapolis police officer Derek Chauvin ended Thursday with Chauvin invoking his constitutional right not to testify and a prosecution expert briefly taking the witness stand. Jurors are likely to begin deliberating Monday.

Closing arguments are scheduled for Monday, moving the trial into its seventh week. Jurors will be immediately sequestered for deliberations as they consider the charges facing Chauvin in the May 25 death of George Floyd — second-degree murder, third-degree murder and second-degree manslaughter.

"I will invoke my Fifth Amendment privilege today," Chauvin told the court Thursday morning. The Fifth Amendment protects against self-incrimination.

Chauvin's brief remarks in response to questions from his attorney, Eric Nelson, and Hennepin County District Judge Peter Cahill were the most he's spoken publicly since kneeling on Floyd's neck for about 9 ½ minutes last year when arresting him for using a fake $20 bill to buy cigarettes.

Chauvin took off a blue surgical face mask, mandated by the courts for COVID-19 protection, and spoke into a microphone in his hand. Jurors were not present for the discussion.

Nelson reminded Chauvin that "the state would have broad latitude" to cross-examine him as a witness if he testified. Nelson and Chauvin told the court they had "repeatedly" discussed whether to testify.

"We have gone back and forth on the matter would be kind of an understatement, right?" Nelson asked Chauvin.

"Yes, it is," Chauvin said with a small hint of a smile.

Nelson asked Chauvin if they had a "lengthy" meeting Wednesday night about testifying that led to "further discussion."

"Correct," Chauvin said, adding that he would not testify.

"The decision whether or not to testify is entirely yours," Cahill told Chauvin after his discussion with Nelson. "In other words, it's a personal right. … Is this your decision not to testify?"

"It is, your honor," Chauvin said.

The judge asked if he had any questions. He said no. The judge asked if anyone had made promises or threats to influence his decision.

"No promises or threats, your honor," Chauvin said.

Cahill asked Chauvin if he wanted jurors to receive a special instruction on the issue, which is offered by the courts when defendants choose not to testify. Chauvin said yes.

"The state must convince you by evidence beyond a reasonable doubt that the defendant is guilty of the crime charged," according to the instruction Cahill recited Thursday. "The defendant has no obligation to prove innocence. The defendant has the right not to testify. This right is guaranteed by the federal and state constitutions. You should not draw any inference from the fact the defendant has not testified in this case."

The defense officially rested its case several minutes later with jurors in attendance. Nelson called seven witnesses between Tuesday and Wednesday.

Arthur Reed, one of Floyd's cousins, watched the proceeding from the lone seat in the courtroom designated for a Floyd family representative. COVID-19 safety protocols have severely limited the number of attendees. A woman sat in a seat Thursday reserved for Chauvin's supporters. She declined to identify herself to a reporter.

Asked outside the courtroom about Chauvin's decision not to testify, Reed said he believed the prosecution "would have chopped him down second by second" were he asked why he remained on Floyd for more than nine minutes.

"We didn't think they were going to put him on at all," Reed said. "We're just ready to get this over with, make sure [Floyd] gets the justice he deserves. We think the state has put on an excellent case."

Chauvin is the fourth officer in Minnesota to be tried for killing a civilian on the job and is the only one who has not testified at his trial.

Officers Jeronimo Yanez and Mohamed Noor and deputy Brian Krook testified when they were tried. Yanez and Krook were acquitted. Noor was convicted.

Prosecutor Matthew Frank later said the state objected to jurors receiving the instruction Cahill recited about Chauvin not testifying, which would be given to them next week after closing arguments. The issue will be resolved when instructions are finalized.

Prosecutors recalled their pulmonologist and critical care expert, Dr. Martin Tobin, to the witness stand Thursday morning to rebut testimony Wednesday from defense witness, pathologist Dr. David Fowler.

Fowler, who recently retired after 17 years as the chief medical examiner for the state of Maryland, testified that Floyd died of cardiac arrest combined with drug use. The prosecution's witnesses previously testified that Floyd died of low oxygen as Chauvin and two other officers pressed him stomach-down in the street.

The Hennepin County Medical Examiner's Office ruled Floyd's cause of death "cardiopulmonary arrest complicating law enforcement subdual, restraint, and neck compression." It also listed hardening and thickening of the artery walls, heart disease and drug use as "other significant conditions." Fentanyl and methamphetamine were also found in Floyd's system.

Fowler had also testified that carbon monoxide from a nearby squad car, which was a hybrid vehicle, was "another brick in the wall" contributing to Floyd's death.

Tobin testified Thursday that he disagreed with Fowler's contention that Floyd's blood could have contained anywhere from 10 to 18% of the poisonous gas.

Autopsy results showed Floyd's blood had an oxygen saturation level of 98%, meaning, "all there was for anything else was 2%," Tobin said, adding that humans typically have anywhere from 0 to 3% of carbon monoxide in their blood at any given moment.

Before Tobin took the stand, prosecutors told the court they were contacted by Hennepin County Chief Medical Examiner Dr. Andrew Baker Wednesday following Fowler's testimony and were made aware of test results that specifically measured the carbon monoxide in Floyd's blood. Prosecutors asked to introduce the evidence in court Thursday through Tobin's rebuttal.

Nelson objected, arguing that Fowler had shared his report with prosecutors in February and had noted he would testify about carbon monoxide, yet prosecutors failed to react until now.

"All of this they had ample time to do, but they're doing it in the middle of trial," said Nelson, who described the prosecution's move as "incredibly prejudicial to the defense."

Fowler was on a plane and could not be reached about the sudden development, Nelson told the court.

Cahill ruled that Tobin could testify about how carbon monoxide could have affected Floyd, but could not mention the test results. "If he even hints at test results the jury has not heard about, it's going to be a mistrial, pure and simple," the judge said. "This late disclosure is not the way we should be operating here."

The judge said although he found the late disclosure "odd," he did not believe the prosecution was acting with ill intent.

Prosecutor Jerry Blackwell said they had broader, previously disclosed blood test results that Tobin would cite.

At the close of Tobin's rebuttal, Cahill told jurors to bring luggage to court Monday in preparation for their sequestration, during which they will be in a hotel and prohibited from returning home.

"If I were you, I would plan for long and hope for short. … Whether it's an hour or a week, it's entirely in your province," Cahill said.

Two former Minneapolis police officers who helped restrain Floyd, J. Alexander Kueng and Thomas Lane, and a third who kept angry bystanders at bay, Tou Thao, are scheduled to be tried Aug. 23 on charges of aiding and abetting second-degree murder and manslaughter.

All four defendants, who were fired, are out on bond.