May I pose a question?
From what I saw, and I may be mistaken, the door had a metal gate. Where I am from, we have the metal gate for security reasons, and if we answer the door we usually stand behind it and look around to see who is ringing.
Now, and bear with as I am slow in the mornings (and not much faster the rest of the day), the doorbell camera lets you know who it is, and you go to open IF you recognize the person, ESPECIALLY late at night.
My point, and I do have one if you give me a moment to get to it, is that if NG went to the door, she KNEW who it was. If she didn't and she opened, she did it cautiously (one hopes), and the metal gate would be (again, one hopes) locked. It will, as is the case with storm doors, open out towards the porch, and she would have been behind the door that opens IN towards the house.
This scenario would indicate that, if she indeed opened the front door, she knew the person who rang, and was welcoming them into the house. Forcing their way in would require a key for the gate, and if they have a key for the gate, WHY RING?
Again, my own thoughts, and I meander, but I grew up in a household of old people (raising me as a child) and we had gates and doors, and old people habits (which I now obviously exercise in an age-appropriate manner.)
Oh, and we have solar powered security cameras that announce people on the driveway, the walkway to our door, our porch, our side gate and our back door...unless we are expecting someone, or recognize who is on our property, we do not open.
My own opinions and thoughts and it's time for a second cup of coffee so forgive me if I've been nonsensical.