[user104658]

IF it's found that they were indeed strangers and had no personal connection / there had been no dispute between them (a noise dispute is possible, given that it's directly above?) or anything like that, then I'm inclined to believe it based on that report. If the hallways all look the same, and she simply absent-mindedly drove her car up one too many levels in the parking garage, then it is feasible that she thought she had returned to her own apartment and found the door ajar / someone inside.

A tragic misunderstanding if so.

However, ONCE AGAIN, it does strike me that if this had happened in the UK, she would NOT have been carrying a lethal firearm. She would have shouted or screamed or said "Who the **** are you, get out!!", MAYBE she might have thrown something at him, and then they would have both realised the mistake and probably have had a good laugh about it and told the story for years to come. Instead, she was able to put a bullet in him in seconds before anyone had time to think.


Which also makes me realise, in the story above where me and my friends went to the wrong house and started trying to get in / shouting at the windows... in a large number of US states... we might well have been ****ing shot .