Why would someone knock on my window at 2 am?

So it been two days in a rows that some person (I don't know if men or woman but it seem to be a man) that knock on my window (he did it 3 time and was more and more agressive the more he did it) and then today I hear him roaming during 1 hours around my house, I'm extremely scared I didn't answer it and went to bed.

I thought it was just a druggies the first time or something trying to get some light for his cigarette but two days in a row is ways creepier especially since I heard him whistle and roaming around my house for 1 hours...

I don't know what to do is it so creepy and the police don't come in my area because there's too many druggies, drugs dealer and criminals in general.

Why would someone knock on my window at 2 am?
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