iStock/ThamKCBy: IVAN PEREIRA, ABC News

(NEW YORK) -- An independent autopsy ordered by George Floyd's family found his death was a "homicide caused by asphyxia due to neck and back compression that led to a lack of blood flow to the brain," according to early findings from the examination released Monday.

Floyd was apprehended by police officers in Minneapolis, Minnesota, last Monday, and one of the officers pinned his knee to Floyd's neck as Floyd called out that he couldn't breathe.

The independent examiners found that weight on Floyd's back, the handcuffs and the positioning were contributory factors because they impaired the ability of Floyd's diaphragm to function. The report concluded that Floyd, 46, died at the scene.

"The ambulance was the hearse," Ben Crump, an attorney for Floyd's family, said at a news conference announcing the findings.

Later Monday, the Hennepin County Medical Examiner's office released its initial findings of their autopsy and also declared Floyd's death was a homicide caused by "a cardiopulmonary arrest while being restrained by law enforcement officer(s)."

Dr. Michael Baden and the University of Michigan Medical School's director of autopsy and forensic services, Dr. Allecia Wilson, handled the newly announced independent examination.

Baden, who was New York's medical examiner in 1978 and 1979, had previously performed independent autopsies on Eric Garner, who was killed by a police officer in Staten Island, New York, in 2014 and Michael Brown, who was shot by officers in Ferguson, Missouri, that same year.

Baden said Floyd was in good health before his death and said the video of his death showed the compression of his neck and back very clearly.

"When he said 'I can't breathe,' unfortunately, many police are under impression that if you can talk that means you're breathing. That is not true," he said during the news conference.

Wilson said toxicology reports and other examinations are still ongoing and acknowledged that since they conducted a second autopsy, as the medical examiner had done one previously, they did not have access to Floyd's tissue samples in their original state.

"We feel those items will not change or alter the cause of death with mechanical asphyxia," she said.

The medical examiner's preliminary report, however, said Floyd had "other significant conditions," including "arteriosclerotic and hypertensive heart disease, a fentanyl intoxication and recent methamphetamine use."

Former Minneapolis police officer Derek Chauvin, identified as the officer who put his knee to Floyd's neck, was arrested and charged with third-degree murder and manslaughter. Floyd was heard saying "I can't breathe," while the officer had him pinned for nearly nine minutes, according to the criminal complaint.

Three other officers who were involved in the arrest have been fired but haven't been charged as of Monday afternoon.

The criminal complaint said the official examination of Floyd's body by the medical examiner is still ongoing, but prosecutors provided some information about this death. This is separate from the independent autopsy requested by Floyd's family.

The medical examiner's initial findings were that Floyd had underlying health conditions including coronary artery disease and hypertensive heart disease, the complaint said.

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