The updated report came just hours after the Floyd family released their own independent autopsy report, which was at odds with Hennepin County's initial findings.
The two independent medical examiners who performed the autopsy on behalf of the Floyd family ruled Mr Floyds' death was a homicide caused by “mechanical asphyxia".
Dr Michael Baden, one of the doctors who performed the autopsy as the behest of Mr Floyd’s family, said during a news conference in Minneapolis that the 46-year-old had no underlying medical conditions that contributed to his death.
Dr Baden said Mr Floyd's death was caused pressure on both the man’s neck and by the knees of two officers on his back.
He said there would not be physical evidence of the compression on Mr Floyd's neck and back.
"It can only be seen while the compression is being applied, or when as in this instance it is captured on video," he said.
Those results contradicted preliminary findings by the Hennepin County Medical Examiner's Office that Mr Floyd died from a combination of factors, including possible substances in his system and underlying medical conditions.
Ben Crump, the civil rights attorney who represents George Floyd's family, had previously suggested that the Hennepin County coroner's investigation might be intended to create a false narrative of the arrest.
"George Floyd was a healthy young man," he said.
"The officers killed him based on a knee to his neck for almost nine minutes, and two knees to his back compressing his lungs."
Governor Tim Walz has put the attorney general, Keith Ellison, in charge of the prosecution following requests from the Floyd family.
The Hennepin County Attorney's office has been accused of unnecessarily delay in filing the charge against Chauvin, and of failing to charge the other three officers who were at the scene.
Meanwhile, dozens of cities across the United States remain under curfews at a level not seen since riots following the 1968 assassination of civil rights activist Martin Luther King Jr.
The National Guard deployed in 23 states and Washington, D.C.
Curfews were extended in Washington, D.C., where authorities fought to put out fires near the White House overnight; in Minnesota, which has experienced some of the worst violence, and in Los Angeles.
One person was killed in Louisville, Kentucky, overnight where police and National Guard troops returned fire while trying to disperse a crowd.
Police in Chicago, the country's third-largest city, fielded more than 10,000 calls for looting, Mayor Lori Lightfoot told a briefing.
The unrest, which erupted as the country was easing lengthy lockdowns to stop the spread of the coronavirus, began with peaceful protests over Mr Floyd's death.
Derek Chauvin, a since-fired 44-year-old officer, has been charged with third-degree murder and second-degree manslaughter. He was released on $500,000 bail and is due to appear in court on June 8, according to jail records.
On Monday, dozens of people quietly paid their respects to George Floyd at the scene outside the Cup Foods where he lost his life.
Visitors left flowers and signs honouring Mr Floyd on the pavement.
A little girl wrote, “I’ll fight with you,” in aqua blue chalk in the road.
"This is therapeutic. My heart was real heavy this morning so I came down extra early and when I got here, the heaviness lifted,” said Diana Jones, 40, the mother of four children.
“This right here let’s me know that things are going to be ok.”
Terrence Floyd, the victim's brother, told the gathering he wanted people to get educated, vote and not destroy their own communities.
"Let's do this another way," he said.