Defense lawyers at the murder trial of ex-Minneapolis cop Derek Chauvin claimed Wednesday that exhaust fumes from a police vehicle at the scene contributed to George Floyd’s police custody death.

David Richard Fowler, a retired Maryland forensics expert, told jurors that while Floyd did not die from carbon monoxide poisoning, it was a “contributing condition” in his May 25 death while pinned down.

“His face was facing towards the vehicle, towards the rear of the vehicle, and directly towards the area where you would expect the tailpipe or the tailpipes of the vehicle to be,” Fowler testified.

“Let me ask you,” Chauvin’s lawyer Eric Nelson said. “Are you suggesting that Mr. Floyd died from carbon monoxide poisoning?”

Absolutely not, no,” Fowler answered. “Not a full carbon monoxide poisoning. No.”

But he also noted that he did not believe the coroner who performed Floyd’s autopsy checked his blood for carbon monoxide.

It’s the first time vehicle exhaust has been mentioned in connection with Floyd’s death.

Viral video of Floyd’s death shows Chauvin restraining Floyd with his knee on his neck for more than nine minutes, with Floyd face-down on the ground at the rear of a Minneapolis police SUV.

In earlier testimony, Fowler said there were several contributing factors that led to Floyd’s death, including heart disease, and fentanyl and methamphetamines that were found in his system following his death.

“During his restraint and subdual by police or restraint by the police, and then his significant contributory conditions … he would have the toxicology, and fentanyl and methamphetamine,” Fowler testified.

“There is exposure to a vehicle exhaust, so potentially carbon monoxide poisoning, or at least an effect from increased carbon monoxide in his bloodstream,” he said. “So, all of those combined to cause Mr. Floyd’s death.”

Prosecutor Jerry Blackwell grilled Fowler on cross-examination, accusing him of trying to “confuse the jury.”

“You spent quite a bit of time talking about carbon monoxide. You remember that discussion, don’t you?” Blackwell asked Fowler.

“I do indeed,” he answered.

“Now, just going right to the punchline of carbon monoxide that you talked about at some length,” Blackwell continued. “You haven’t seen any data or test results that showed Mr. Floyd had a single injury from carbon monoxide, is that true?” Blackwell asked.

“That is correct because it was never…” Fowler began.

“I asked you if it was true or not,” the prosecutor interrupted. “Yes or no?”

“It is true,” Fowler answered. 

Prosecutors have argued throughout the trial, now in its third week, that Floyd died as a result of Chauvin’s restraint, which left him unable to breathe for several minutes.

Defense lawyers began presenting their case this week, with the trial expected to wrap up this week and move to closing arguments Monday,

Chauvin is charged with second-degree murder, third-degree murder, and second-degree manslaughter in Floyd’s death.