A quick Googling says that most users can get 50 yards (45 meters) with no issues on a calm day, and this shooter is supposed to be good at this, so I'd say 80 yards (73 meters)—which normal people practice from for shits and giggles—should be doable for them, and that'd be the next street over with modern roads even when you take into account things like the distance from the roof on one side of the street to the other.
What I'm getting at is, if this assassin really is an expert, I feel like they should have tried this from at least a street over, which would be much harder to spot. And if they're not an expert, what are they even doing here?