re: Why does New Orleans have more murders than similar cities?

"Mitch spent $40M of federal funds on cameras and effectively gave up on preventing crime and invested in solving it"

I think you're right with regard to the current increase. At a minimum, the two are closely related in time. Probably hard to show causation, but many New Orleanians believe this and it sure seems true.

"also, the lack of segregation in Nola between economically different areas creates more crime. violent crime occurs in areas where polar classes meet"

At least with respect to murder, this almost can't be correct. If the "checkerboard" nature of New Orleans were to blame, you would expect to see more murders of white and upper class citizens but such people represent a tiny sliver of murder victims.