goddammit. Nothing good can ever happen.
I would imagine that most of the doors just have a normal knot or loop and maybe that is why they didn't recognize it? Because unless your trying to lynch someone or send a really racist message a noose seems like a really extremely complex and wasteful knot job ( i know nothing of knots)
So was it tied differently from the other ropes in the area that are still attached to the garage doors(I know you don't have the answer, I am just asking rhetorically)? Because if it was then that seems to me like even if the rope was looped like normal and then broke, someone came back and retied it like a noose, which would imply some kind of maliciousness. If it was just tied like the other ropes there, someone should have recognized what it was. Something is not adding up here.