Fear is the problem here
We used to run around the neighborhood at night playing tag all the time. Now you have to worry a homeowner will shoot you if you hide in their bushes. Statistically crime is down yet the informational age has so "enlightened us to the possibilities" many think the worst case scenario when they hear a noise outside. The father's sister called him when she detected a prowler. Call the cops first. He should of just gone over and sat with her till they got there. How could you live with yourself after doing something like this? I couldn't.
Identifying an intruder? - easy someone you don't recognize in a place you don't expect them. now recognizing a credible threat thats the real question. for sure one should not go looking for it.