MINNEAPOLIS - Derek Chauvin spoke publicly for the first time since his arrest in May, telling a judge Thursday that he would invoke his constitutional right against self-incrimination and not testify in his own defense in his murder trial in the death of George Floyd. 

The defense rested its case minutes later, after just two days of testimony, paving the way for closing arguments and jury deliberations in the landmark trial to begin Monday.

In a dramatic moment outside the view of the jury, the former police officer removed his face mask inside the downtown Minneapolis courtroom where he has sat silently and stoically day after day through jury selection and weeks of intense testimony about the night Floyd died while pinned beneath his knee.

Chauvin held a microphone, nodding and even smiling at moments as his attorney, Eric Nelson, recounted for the court how the two men had "gone back and forth" about whether he should take the stand, including one final "lengthy meeting" on the issue Wednesday night.

"I will invoke my Fifth Amendment privilege today," Chauvin told the court, the first sentence he has spoken publicly since his arrest in Floyd's killing nearly one year ago. His voice, deep with a clear Upper Midwestern dialect, has only been heard briefly in the litany of police body camera and bystander footage of the night Floyd died that has been repeatedly played in the courtroom.

"It is your decision to not testify?" Hennepin County Judge Peter Cahill asked him.

"It is, your honor," Chauvin replied.

The moment ended weeks of intense speculation, including among prosecutors, about whether Chauvin would take the stand and attempt to explain what he was thinking when he knelt on Floyd's neck and back for over nine minutes. Floyd was handcuffed, face down on a street, begging for breath and calling for his deceased mother until he went limp.

Several jurors indicated during jury selection that they were interested in hearing Chauvin's side of the story. And some observers believed his testimony might have been the only way to undo some of the damage from weeks of deeply fraught testimony from prosecution witnesses, including young people at the scene who told the jury of the "cold look" on Chauvin's face as he knelt on Floyd's neck, and the fear and helplessness they felt as they watched the Black man die.

It might also have given Chauvin an opportunity to express remorse for Floyd's death or show more of his humanity. In the courtroom, the former officer, much of his face concealed by a blue surgical mask, has often appeared stiff and uncomfortable as footage of him atop Floyd played for the jury. He often seemed to avoid looking toward jurors during especially emotional testimony, including from Floyd's younger brother, Philonise, who appeared as the prosecution's "spark of life" witness last week.

But the move also would have presented a risk for Chauvin, who would have faced intense cross-examination by prosecutors who likely would have pressed him to respond to damaging evidence in the case.

That evidence includes body camera footage that showed another officer at the scene telling Chauvin he could not find Floyd's pulse - to which Chauvin responded by keeping his knee on the man's neck for at least two more minutes - and testimony from several of his former Minneapolis police colleagues, including Chief Medaria Arradondo who told the jury that Chauvin violated policy and training with his restraint of Floyd.

But the legal risks wouldn't end there for Chauvin, who is charged with second- and third-degree murder and second-degree manslaughter in Floyd's death. He and the other officers at the scene - Alexander Kueng, Thomas Lane and Tou Thao - are also the subject of a federal civil rights investigation into Floyd's death.

As Chauvin's murder trial has played out, a federal grand jury has heard testimony from several of the same witnesses - including Hennepin County Chief Medical Examiner Andrew Baker, who said last week he had testified twice before the grand jury.

Federal officials have repeatedly declined to comment on the grand jury. But a source familiar with the investigation, who spoke on the condition of anonymity because the proceedings are not public, said the panel is also believed to be examining Chauvin's past uses of force - before he was fired after Floyd's death - evidence Cahill ruled was inadmissible in the state's criminal trial.

Still, Nelson indicated Thursday that he and Chauvin had debated his potential testimony at length, and as of Wednesday, some close to the case believed he might take the risk after two days of defense witnesses whose testimony at times seemed more beneficial for the prosecution.

Attorneys who have represented police officers say these cases are unlike any others. They describe police officers as good clients because they usually have clean criminal records and are already experienced at testifying in court. Deciding whether to have the officers testify during their own trial can be a critical decision, they said.

"That's the 3 o'clock in the morning question when you wake up and think about the case," Neil Bruntrager, a Missouri attorney who has represented officers, said in an interview before Chauvin's trial began. "You wake up thinking about that question: Do I put him on?"

Arthur Reed, Floyd's cousin who sat in the courtroom Thursday as Chauvin announced he would not testify, said afterward he was not surprised by his decision to invoke his Fifth Amendment rights. Reed said the prosecution "would have chopped him down second by second" about why he had knelt on Floyd so long.

"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 he gets the justice he deserves. We think the state has put on an excellent case."

Chauvin's decision effectively ended the defense case, which called just seven witnesses over two days - far less than the three dozen prosecution witnesses who appeared over a span of two weeks.

On Thursday, prosecutors recalled Martin Tobin, the Chicago-area pulmonologist who testified last week in excruciating detail about Floyd's fight for breath. He appeared as a rebuttal witness to challenge testimony from David Fowler, the former Maryland state medical examiner and chief forensic witness for the defense, who floated a theory Wednesday that Floyd may have died of carbon monoxide poisoning.

Fowler argued, citing no evidence, that Floyd's blood could have contained between 10 and 18 percent of the poisonous gas, since he was positioned on the ground near the exhaust pipe of a police squad car - though the doctor later admitted he wasn't certain the car was running. Fowler admitted his numbers were estimates because he had not seen evidence that Floyd's blood had been tested for the gas.

But Tobin pointed to autopsy results showing Floyd's blood had an oxygen saturation level of 98% - meaning "anything else" in his blood would have measured at just 2%, well within the normal range of carbon monoxide in people's blood.

Fowler's claim, Tobin told the jury, was "simply wrong."

In an unusual turn of events, prosecutors said they had uncovered new evidence overnight that Floyd's blood had been tested for carbon monoxide when he was taken to Hennepin County Medical Center the night of his death, but that the results hadn't been turned over by the country in its response to a subpoena.

Prosecutor Jerry Blackwell told the court they had been made aware of the test results by Baker, the medical examiner, who called them after watching Fowler's testimony. But Cahill blocked the evidence, saying prosecutors had known of Fowler's planned testimony since late February and could have investigated the missing blood results earlier. He said if Tobin mentioned the results it could result in a "mistrial, pure and simple."

The court recessed shortly thereafter, with Cahill telling the jury to enjoy a long weekend before returning to court Monday with a packed bag to hear closing arguments and to sequester as they deliberate a verdict.

Cahill said the court had received questions from jurors about how much they should pack. "If I were you, I would plan for long and hope for short," the judge said. However long it takes to get a unanimous verdict, he added, "whether it's an hour or a week, it's entirely within your province."

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The Washington Post's Mark Berman contributed to this report.