What *can't* be explained in an innocent way is the cop having been directed to the wrong apartment.
Yeah, might be “unwise” if it is truly a cop at your door...but the home invasion robber can yell out “Police, open up” too. Going to your own door with a firearm at your side (even for a real cop at the door) should not be a death sentence. The video here (top of the page) edits out the few key frames just after the door opens...cannot tell if the gun was pointed or not:
https://www.newsweek.com/roger-fortson-killed-florida-deputy-benjamin-crump-1898963