Derek Chauvin trial told autopsy is ‘only a tiny part of the death investigation’

The trial of former police office Derek Chauvin entered a difficult phase for the prosecution on Friday as it sought to explain why the state autopsy on George Floyd came to conclusions about the cause of his death apparently at odds with evidence given by a string of medical experts over recent days.

Dr Lindsey Thomas, a forensic pathologist and medical examiner brought in to review the official autopsy, told the trial that it is “only a tiny part of the death investigation” of the 46 year-old after it left open the exact cause of death.

Related: George Floyd died from lack of oxygen caused by restraint, lung expert testifies

A succession of medical experts has attributed Floyd’s death to “lack of oxygen” because of the position he was held in by the police. The defence says the autopsy does not directly attribute it to asphyxia.

Thomas said that the autopsy findings do not take into account wider evidence, such as Floyd’s neck being held down under Chauvin’s knee for more than nine minutes, but she was in no doubt that he died because he couldn’t breathe.

“The activities of the law enforcement officers resulted in Mr Floyd’s death, and that specifically those activities were the subdual, the restraint and the neck compression,” she said.

Thomas was called in by the prosecution to investigate Floyd’s death after the Hennepin county medical examiner, Dr Andrew Baker, concluded it was caused by “cardiopulmonary arrest complicating law enforcement subdual, restraint and neck compression”. Baker also listed hardening and thickening of the artery walls, heart disease and illicit drug use as “other significant conditions”.

Chauvin’s lawyer, Eric Nelson, said in his opening statement that this was evidence Floyd died of heart problems combined with drug use. Thomas said that ultimately everybody dies of cardiopulmonary arrest, which is no more than the stopping of the heart and lungs, and that it was not the cause of death.

Chauvin, 45, has denied charges of second- and third-degree murder, and manslaughter, over Floyd’s death last May which prompted mass protests for racial justice across the US and other parts of the world. He faces up to 40 years in prison if convicted of the most serious charge.

The defence has claimed that the prosecution called Thomas to investigate Floyd’s death because it did not like Baker’s findings and so tried to come up with more conclusive ones.

The prosecution used Thomas, who helped train Baker many years earlier, to try to show that the autopsy findings are not at odds with the past three days of testimony from medical experts that Floyd died from lack of oxygen and that drugs were not a factor as the defence claims.

Asked about the death certificate’s listing of “other contributing conditions”, including heart disease and drug use, Thomas said that does not mean they directly contributed to the cause of death and are often listed for medical data collection purposes. She said that heart problems and the drugs found in Floyd’s system would have resulted in a different kind of death if they had killed him.

Nelson won some concessions from Thomas who agreed that Floyd’s heart condition “was a potential cause of death”. She said he had an enlarged heart with narrowed arteries and probably high blood pressure.

Nelson asked Thomas what she would have concluded was the cause of death if Floyd had been found in the same condition but the police had not been involved. She said she would likely have found that he died of heart disease.

Nelson also put it to her that decreased oxygen to the brain can be caused by the use of illegal drugs.

“Some controlled substances affect the ability to breathe,” she agreed.
Thomas agreed that in some circumstances, the amount of drugs in Floyd’s body could be considered an overdose.

But Thomas later said that it did not make sense to exclude the part played by the police in assessing the cause of death.

Baker is expected to give evidence after Thomas and can expect to be grilled by the defence on his more equivocal findings.

Documents obtained by the Star Tribune in Minneapolis show that Baker was less certain than other experts about the degree to which the actions of Chauvin and the other officers contributed to Floyd’s death.

He concluded that the arrest placed added stress on Floyd’s already damaged heart and increased the likelihood of a “bad outcome”. But he also questioned a key plank of the prosecution’s case that Floyd being held down with three officers putting their weight on him was dangerous.

On Thursday, Dr Martin Tobin, a pulmonary specialist, told the trial that Floyd died when he was caught in a “vice” between Chauvin and the street as the breath was squeezed out of him.

Three other police officers involved in Floyd’s death are scheduled to be tried together later this year on charges of aiding and abetting murder and manslaughter.

The trial continues.