If the man were perceived as a danger, they could have always hog-tied him with plastic restraints --- the wrists and the ankles tied together and joined behind his back crossways.  Use strong enough ties, and it would take an awfully robust person to snap them in two.  Immobilizing the suspect could be done.  But they didn't have to kill him.

There isn't another country on the face of the earth, where if a vast percentage of the crime in that country were committed by one certain easily identifiable demographic, the courts and law enforcement would go as gently on that demographic, as we do.  Not supposed to profile, not supposed to give it a second thought if a person of that demographic is acting suspicious, or running away from the scene of a crime.  Black people themselves --- the vast majority of whom are law-abiding, responsible, solid citizens --- will admit, if pressed, that they fear young black males on a dark street, or in a dodgy section of town.

But they shouldn't have killed the man, and they shouldn't have treated him any more roughly than they would have treated any other suspect.

Just the other day, a local political candidate called me asking for my vote, young black man, attorney, respectable member of the community.  I asked him if he supported a woman's right to choose.  (Note that I phrased it in such a way that he would just assume I was pro-choice myself, even though I said nothing of the sort.)  He said yes, Roe v Wade is the law of the land, during the first trimester, he supported abortion choice.  I thanked him and told him he said exactly what I needed to know.

I hope nobody ever thinks his life isn't worth defending. All lives matter.

I have followed this pretty closely, and discussed it with a few people in the comments section of Foxnews. I will number some things I consider significant about this:
1)  There is 7 minutes of time between his handcuffing and when he was on the ground when there was NO VIDEO for those minutes. The officers say the man was resisting getting into the car. We don't know how violent the resistance was, but his being on the ground in the other video is a result. The amount of force police use at their discretion is based on factors such as the level of violence and how big the man is.
2)  I know of no witnesses saying the man was not resisting arrest.
3)  No experienced officer in his right mind would do blatantly wrong things in broad daylight on a busy street.
4)  There is no particular method to subdue the unruly. It's up to the officer to decide according to the situation, and in context of everything surrounding him.
5)  I have read that police know a method of subduing a standing man by an arm hold around the neck, where the bent of the arm is in front of the neck and the upper arm and forearm on each side. Squeezing can depress a major vein and make the suspect black out very quickly.
6)  The officers knee was on the BACK of the neck and somewhat towards the side. We don't know the pressure. But had it been pressing on the vein, the man would have blacked out quickly. He didn't, so that means the vein was not being pressed.
7)  The officers knee was not in a position to interfere with the windpipe, so he could not be strangled. The fact that the man was capable of speaking loudly and repeatedly shows he was not suffocating.
8)  Arrested suspects are often known to lie and try to make the police feel guilty for how they are being treated, often as a diversion to be able to run or grab a weapon.
9)  No experienced officer would deliberately strangle another man in broad daylight especially when the act is not quick but takes minutes. It's obvious the officer did not think the suspect would be caused serious harm.
10)  Come to know, the suspect had other health problems, such as hypertension, which can easily result in a heart attack.
11)  Suspects have been known to die by an officer's use of a taser. In those cases the officers don't mean to cause any serious harm either, but it happens.

I found out that the autopsy shows the cause of death was NOT strangulation. The family is hiring another doctor to do a second autopsy.

It was said that the man was about to be put into the police cruiser and stiffened up and fell saying he was claustrophobic. This was a plain lie because the man was just taken out of his own car minutes before. Criminals can play games like this to give them time to think about their next move, or give time for an accomplice to spring them. It was a dangerous situation. Since it was not strangulation, the man was also lying about not being able to breathe.