Here's my take, Archidamus.
Had the Superdome been filled with a similar number of people from one of the black middle-class suburban neighborhoods of Atlanta, the racial composition would have been same, but there would not have been the murders, rapes, muggings, etc that we have read reports of.
While many other jurisdictions, such as New York City under Giuliani, paid close attention to social theorists such as James Q. Wilson and his "broken window theory" of crime, New Orleans apparently did not. While in much of the United States, civil and law enforcement authorities understood the importance of making extra efforts to raise their conviction rates and keep hardened criminals off the street longer, with the result that such criminals have less influence on the young people in their neighborhoods, and that crime rates dropped dramatically, and that the cultural atmosphere considerably improved, New Orleans apparently did not.
The blame lies first with those scumbags who are the criminals, but secondarily, with liberal policies that failed the people of New Orleans and these unfortunate foreign visitors.
"It's the culture, stupid"
We await formal complaints, interviews by experienced investigators, and presentation of other evidence.
Their "solution" has been to abandon infested houses ~ which just about all anyone can do. Unfortunately, they did not have a vigorous program of removing them.
The result is that most New Orleans neighborhoods end up filled with abandoned houses. That, in turn, leads to the "Detroit Syndrome".