George Floyd was killed in a homicide caused by asphyxia due to neck and back compression, an independent autopsy found

• George Floyd died on May 25 of asphyxia due to compression of the neck and back, an independent autopsy found.
• A video that has sparked outrage across the nation showed a white Minneapolis police officer pinning the handcuffed 46-year-old black man's neck on the ground beneath his knee.
• The way he was restrained restricted not only "blood flow into his brain, but also airflow into his lungs," said Antonio Romanucci, an attorney working with the Floyd family.
• These findings contradict a Hennepin County Attorney's Office autopsy that found no evidence of "traumatic asphyxia or strangulation."
• The attorney Ben Crump thanked thousands of people for protesting police brutality and demanding justice on Floyd's behalf but said that "the violence is absolutely unacceptable."

George Floyd died on May 25, handcuffed and gasping for breath, pinned under the knees of three white Minneapolis police officers.

Ben Crump, an attorney representing Floyd's family, announced in a Facebook Live broadcast on Monday that an independent autopsy found that the 46-year-old black was killed by asphyxia due to compression of the neck and back.

"We acknowledge that additional medical information including toxicology and further investigation are necessary for a final report," said Dr. Allecia Wilson, the director of autopsy and forensic services at the University of Michigan. "However, the evidence is consistent with mechanical asphyxia as the cause of death and homicide as the manner of death."

Antonio Romanucci, another attorney working with the family, said two "physical mechanisms" killed Floyd, calling it "the lowest level of human respect and dignity that any community should ever have to endure."

'The ambulance was his hearse'

The weight of the arresting officer Derek Chauvin's knee on Floyd's neck — as well as the knees of two other officers who pressed on Floyd's back — stopped not only "blood flow into his brain, but also airflow into his lungs," Romanucci said.

"For George Floyd, the ambulance was his hearse," Crump said. "Beyond question, he would be alive today if not for the pressure applied to his neck by fired officer Derek Chauvin and the strain on his body from the two additional officers kneeing him in his back."

Dr. Michael Baden, a prominent forensic pathologist, added: "The compressive pressure of the neck and back are not seen at autopsy because the pressure has been released by the time the body comes to the medical examiner's office. It can only be seen — serious compressive pressure on the neck and back can only be seen while the pressure's being applied or when, as in this instance, it is captured on video."

Floyd was arrested on May 25 outside Cup Foods after police officers arrived to investigate reports of a forgery. Surveillance footage obtained by NBC News showed that he was sitting in a parked car with a man and a woman. Officers approached the car and led them out of it. Floyd was handcuffed and taken across the street to a police cruiser, out of the frame of the security camera.

The activist Shaun King on Saturday shared a video from another vantage point that appeared to show Floyd struggling with three policemen in the back seat of a squad car while a fourth stood nearby with his hands tucked in his pockets, keeping watch.

After that scuffle, Chauvin pinned Floyd down on the road by his neck. Floyd repeated, "Please, I can't breathe," to which Chauvin replied, "Relax."

The new autopsy contradicts claims from local prosecutors

Baden said Floyd was "motionless" and "lifeless" after about four minutes. An incident report from the Minneapolis Fire Department said that Floyd didn't respond to chest compressions or electric shock.

"Unfortunately, many police are under the impression if you can talk, that means you're breathing. That is not true," Baden said, adding that people like Floyd and Eric Garner should be taken seriously when they say they're struggling for breath.

These findings contradict a criminal complaint by the Hennepin County Attorney's Office that said there were "no physical findings that support a diagnosis of traumatic asphyxia or strangulation."

Floyd had "underlying health conditions including coronary artery disease and hypertensive heart disease," the office's report said, adding that "the combined effects of Mr. Floyd being restrained by the police, his underlying health conditions and any potential intoxicants in his system likely contributed to his death."

Baden said that, however, based on information provided by the victim's family, Floyd "had no underlying medical problem that caused or contributed to his death," adding that he "was in good health."

New information from the Hennepin County medical examiner both echoes and disputes what Crump shared

A few hours after Crump's news conference, the Hennepin County medical examiner reiterated Wilson's finding that Floyd died by homicide and described the cause of death as "cardiopulmonary arrest complicating law enforcement subdual, restraint, and neck compression."

Floyd sustained this injury "while being restrained by law enforcement officer(s)," a press release said. The medical examiner countered Baden's assertion that Floyd had no preexisting health conditions, listing "arteriosclerotic and hypertensive heart disease," "fentanyl intoxication," and "recent methamphetamine use."

Asked by CNN anchor Erin Burnett if the presence of these chemicals in Floyd's body had any relevance to the case, Romanucci said no. He described the police killing as a "but for" case, meaning Floyd would still be alive "but for" the fact that he was so forcefully subdued by Minneapolis policemen that it prompted him to call out the name of his deceased mother before he died

All four officers involved in Floyd's death have been fired, and Chauvin was charged with third-degree murder and manslaughter.

Romanucci said they were all "criminally liable and, without a doubt, civilly responsible." The Floyd family's legal team is pushing for the four policemen to face first-degree murder charges

"Make no mistake about this: This case is about the Minneapolis Police Department and Derek Chauvin and the shameless standby police officers who were on scene who had every opportunity to stop and prevent a senseless death, a needless one" — but didn't, said Romanucci

'Taking a breath for George'

Floyd's family requested the second, independent autopsy. Crump said that the findings would cause them distress but that it was vital for the pursuit of justice.

He said it was "essential that the truth comes out" about the "exact manner and science as to how George Floyd was killed."

Crump used the opportunity to encourage people standing in solidarity with the Floyd family to do so peacefully.

"Had George been alive today and it was some other person, an unarmed, nonthreatening person of color who had been unnecessarily and unjustifiably and senselessly killed by the police," Crump said, he would have been "praying for peace."

Crump thanked protesters for pushing for change and said the Floyd family understood the "righteous anger" that's played out across the United States over the past week. However, he said, "the violence is absolutely unacceptable."

"George died because he needed a breath. He needed a breath of air," he added. "So I implore you all to join his family in taking a breath — taking a breath for justice, taking a breath for peace, taking a breath for our country, but more importantly, taking a breath for George."

This article has been updated.

• Read more:
• Thousands across the UK, Germany, Italy, New Zealand, and Canada condemn racism and demand justice at global Black Lives Matter protests
• Nearly 60% of people left unconscious from neck restraints used by Minneapolis police officers were black, report finds
• A New York police officer drew his gun on protesters. Mayor Bill de Blasio says he 'should have his gun and badge taken away.'
• At least 7 people have been shot and killed in this weekend's anti-police violence protests in the wake of George Floyd's death
• Trump's aides tried to get him to give a unifying TV address, but gave up because he was unwilling and they had no new policies to suggest
• The truck driver who sped through a crowd of George Floyd protesters has been named and booked on suspicion of assault
• Lights at the White House go dark as protests turn violent in Washington
• New video appears to show George Floyd struggling in the backseat of a police cruiser with three Minneapolis officers
• Dennis Rodman has pleaded with people protesting George Floyd's death to stop looting: 'We're not f---ing animals'
• Across America, police violently arrested and shot less-lethal rounds at journalists covering George Floyd and Black Lives Matter protests
• The National Guard says its activated 5,000 troops to respond to unrest in 15 states and DC with thousands more ready to go
• Twitter changed its profile to honor Black Lives Matter amid George Floyd protests
• The Minneapolis police officer who knelt on George Floyd's neck has been arrested. Experts say prosecutors have a long road ahead.
• Derek Chauvin had 16 complaints made against him that were closed with 'no discipline.' A former member of the police review board says that's proof of a broken system.
• People keep sharing the video of George Floyd. Some activists and mental health professionals are calling it 'pain porn' and begging them to stop.
• Most Minnesota law enforcement agencies ban the neck-pinning maneuver used against George Floyd – but it's still allowed in Minneapolis