As I mentioned down-thread, NYC has 45% more violent crime than the national median. It's simply not a "low crime" place, despite the PR.
Obviously in The Bronx the numbers are much worse (9.28), and in Brooklyn they're a tiny bit better (5.43) but still well over USA median. Queens (3.25) is safer than median, though.
Marble hill was once fully a part of the northernmost point of Manhattan island, but a canal was cut south of it which turned Marble hill into an actual island all by itself. Later, the waterway to the north of Marble hill was diverted into the canal, so Marble Hill became connected by land to the Bronx and separated by water from the island of Manhattan, but it is still considered a part of Manhattan borough...
Garbage in, garbage out.