Derek Chauvin chose not to take the stand during his murder trial on Thursday morning (April 15). In what marked the 14th day of his trial, the former Minneapolis police officer told Judge Peter Cahill that he would instead exercise his Fifth Amendment right and decline to testify in his defense.

“I will invoke my Fifth Amendment privilege today,” he said on Thursday.

After Chauvin declined to testify, the defense rested their case. However, prosecutors were allowed to call Dr. Martin Tobin, the pulmonologist who testified last week, back to the stand.

On April 8, Tobin testified that a “low level of oxygen” killed George Floyd, which he said was caused by Chauvin’s knee on Floyd’s neck, the prone position, the positioning of his handcuffs and more.

This statement was challenged yesterday by forensic pathologist Dr. David Fowler, who claimed carbon monoxide from the police car’s exhaust could have contributed to Floyd’s death, among other factors.

However, after Fowler made the claim, prosecutor Jerry Blackwell told the judge they had new evidence regarding the presence of carbon monoxide in Floyd’s blood. Chauvin’s defense lawyer, Eric Nelson, argued that prosecutors should not be allowed to introduce the new evidence at this late stage, and judge Cahill agreed.

Therefore, the judge said Dr. Tobin could return as a witness to refute Fowler’s claims, but ordered him not to discuss the new evidence. If Tobin even mentioned the test results, Cahill said, it would lead to a mistrial.

Tobin rejected Fowler’s claims without discussing the test results and said Fowler’s opinion about carbon monoxide contributing to Floyd’s death was “simply wrong.” The prosecution and defense both rested their cases after Tobin’s testimony and the court adjourned for the day.

The jury is expected to return on Monday (April 19) morning at 10 a.m. EST to hear closing arguments.