you're underestimating the amount of surveillance there is in NYC, every block is under surveillance. two more cameras likely recorded him before he even step foot off that block.
That has nothing to do with having a throwaway gun.
NYC surveillance could catch him if he yelled racial slurs at someone and never shot or put hands on him.
The point of discussion was throwing away the gun.
A majority of murders get solved because crime is not random. Dudes know each other, know people that know both of them, probably went to the same school or rival schools, dated the same chick, hangout at the same night spots, etc. Very very few murders are some person killing an absolute random person for no reason.
they'll catch him or someone else will identify him.