The medical examiner who performed George Floyd’s autopsy took the stand Friday for the tenth day of witness testimony in former Minneapolis police officer Derek Chauvin’s trial to explain how he determined Floyd’s cause of death.

Dr. Andrew Baker, Hennepin County’s chief medical examiner, wrote on Floyd’s death certificate that he died from “cardiopulmonary arrest complicating law enforcement subdual, restraint and neck compression.” His manner of death is listed as homicide, which, to medical examiners, describes a death that occurs at the hands of another person who may or may not have intended to kill.

Floyd, 46, died last May after a struggle with Minneapolis police officers while his hands were restrained behind his back; Chauvin pinned Floyd’s neck to the ground using his knee for more than nine minutes.

While Floyd had heart disease and certain drugs in his system, Baker testified, the cause of death listed must be the “most important thing that precipitated the death” ― in this case, the restraints put in place by law enforcement officers. 

“In my opinion, the law enforcement subdual or neck compression was just more than Mr. Floyd could take by virtue of those heart conditions,” Baker said. 

“Mr. Floyd’s use of fentanyl did not cause the subdual or neck restraint. His heart disease did not cause the subdual or neck restraint,” he added.

Baker’s testimony complemented that of consulting forensic pathologist Dr. Lindsey Thomas, who testified earlier on Friday that Floyd died of asphyxia, or low oxygen. 

“There’s no evidence to suggest that he would’ve died that night except for the interactions with law enforcement,” Thomas told the courtroom. 

She said she had never before seen a case with so much video documentation that clued her in to what the subject’s final moments were really like. 

Much like expert witness Dr. Martin Tobin the day before, Thomas was also able to explicitly say that actions taken by law enforcement led to Floyd’s death. 

“Mr. Floyd was in a position … where he was unable to get enough oxygen in to maintain his body functions,” she said. 

During cross-examination, defense attorney Eric Nelson established that Floyd had certain preexisting conditions and drugs in his system: His heart was slightly enlarged, requiring more oxygen, and he had tested positive for methamphetamine and fentanyl, which can depress breathing.

Nelson’s task throughout the duration of the trial is, in large part, to convince the jury that Floyd’s personal health contributed more toward his death than Chauvin’s actions. 

While methamphetamine use was listed under the “other contributing conditions” section of Floyd’s death certification, Thomas explained that the section of the form is meant to document factors that were present but that which doctors do not believe had an impact on the subject’s death. Such information is useful to researchers and state data collectors, Thomas said. 

Chauvin has pleaded not guilty to the three homicide-related charges against him. If convicted, he could receive a sentence of 11 to 15 years in prison. 

Three other officers who were present at the scene of Floyd’s death will stand trial later this year.