Something similar happened to a lady at church. Her grown daughter was walking in her bedroom with the lights off. The son-in-law, her husband woke up in the dark, assumed it was an intruder, grabbed his gun and shot, killing his wife instantly.
It's a good thing my gun is on my side of the bed. I often walk in and out of the bedroom in the middle of the night with the lights off; I know my way around the house in the dark. The worst I'm facing is my wife clobbering me with the baseball bat she keeps on her side of the bed.
I’m not sure I would buy that story. He didn’t notice that his wife wasn’t in bed?
In the end, I guess it is good enough to be not provable beyond a reasonable doubt.
Here's one where the homeowner shot someone coming into his dark garage. What's bad is that it was his teenage daughter. What was worse, is that he was a Sheriff's deputy, and was stupid.
https://www.freep.com/story/news/nation/2014/08/15/virginia-sheriffs-deputy-shoots-daughter-sneaking-back-home/14097949/
He figured someone had broken into his garage, and fired his gun, then heard his daughter's voice after shooting her.