When your stabbed in the heart there’s precious little they can do for you. The police absolutely did mishandle it though. But the mishandling realistically didn’t contribute to the death. Even if they had immediately applied pressure and chest compression. The odds of survival were truly Vanishing. But handcuffing them and leaving them to die was just callous and unnecessary. But that’s how police operate. You have to remember the average person would have hardly been qualified to handle that situation and the police are always less qualified than that.