An officer, who heard over his radio that a drug suspect was armed with a gun, kicks down the door of his apartment, finds the suspect hiding in the bathroom (probably trying to flush weed down the toilet), thinks the suspect is going for his gun, and shoots and kills the suspect. The problem is that the suspect, according to police, wasn't armed. (Remember this the next time you think officers carry a drop gun.)
The officer made a big bad lethal mistake. And he was very quickly thrown under the bus by the Commissioner and the department. But I don't know what I would have done in the same situation. Probably the same thing. The cop fired not because he wanted to kill an unarmed man and destroy his own life and career, but because he thought he was going to be killed. Unfortunately for everybody, he was wrong.
When this kinds of events happen, don't be be surprised or shocked or outraged. This is what happen with drug prohibition and the war on the drugs. The courts destroy the 4th Amendment. Police bust down doors. Police assume (with the courts' blessing) that drug dealers are armed. Sometimes police make mistakes, and unarmed people get shot.
I wouldn't say it happens all the time. But it sure does happen a lot. And it will continue to happen as long as we keep fighting the bad fight and refuse to seriously consider changing our laws against illegal drugs. In the meantime, let me know when we start winning.