April 14 (UPI) -- A former medical examiner from Maryland called by the defense Wednesday said George Floyd died from cardiac arrhythmia, not asphyxia as prosecutors contend in the murder trial of former Minneapolis police officer Derek Chauvin.
Dr. David Fowler, who worked 17 years as the chief medical examiner of Maryland, said Floyd's heart disease combined with his fentanyl and methamphetamine use, exposure to vehicle exhaust and tumors near his carotid artery all played a part in his death.
He said the methamphetamine use is linked to narrowing blood vessels, increasing risk of arrhythmia and increased heart rate. He said Floyd's heart was also enlarged, making him susceptible to reduced blood supply.
"All of those combined to cause Mr. Floyd's death," he said in testimony on the 13th day of Chauvin's trial.
He didn't mention asphyxiation as a cause of death, directly contradicting testimony from Dr. Martin Tobin, a pulmonologist and critical care physician called by prosecutors.
"Positional asphyxia, as the term is used in court today, is an interesting hypothesis and unsupported by any experimental data," Fowler said while under cross examination.
He said he didn't have any test results to suggest Floyd had carbon monoxide poisoning from breathing in the car exhaust.
Fowler also said officers at the scene of Floyd's arrest should have helped him after they noticed he had no pulse about 5 minutes after he was restrained.
"As a physician, I would agree," he said when prosecutors asked him if the officers were negligent in not providing medical aid.
Fowler was the only witness to give testimony Wednesday.
Floyd died May 25 after Chauvin kneeled on his neck for more than 9 minutes during an arrest on suspicion he used a counterfeit $20 bill at a convenience store. Chauvin has been charged with second-degree murder, third-degree murder and second-degree manslaughter for the death.
Fowler said his assessment of Floyd's case was reviewed by The Forensic Panel, a group of scientists and doctors who offer peer review of forensic cases.
The Minneapolis Star Tribune reported Fowler is the subject of a lawsuit accusing him of covering up the cause of death of Anton Black, a Black man who died in police custody in 2018. The suit said he intentionally delayed the results of Black's autopsy and helped protect the police.
Defense attorneys began their case and the prosecution rested theirs Tuesday after more than two weeks of testimony. Chauvin's attorneys called experts in policing to testify Tuesday that he used appropriate subdual actions when arresting Floyd.