Along the lines of what my theory (FWIW) is.
He was likely trolling the internet and social media, looking for an opportunity such as this.
I’ve been following this story since day one. The one thing that always struck me was the number of selfie style pictures that she had taken. Young kids who take lots of selfies tend to post them to social media. It happens.
I also believe that he may have been an avid computer gamer.
Grand Theft Auto kinda stuff.
He knew how to quickly breach a door with a gauge and storm a building, overwhelming and killing the parents. I’ll bet it was quick.
JMHO.
Thanks, sounds reasonable.