Now that the city of New Orleans is getting back together following the devastation caused by Hurricane Katrina, efforts are under way to examine the emergency plan and how it was implemented.
Nagin has criticised federal authority's response to the disaster
How did this plan go wrong, and who really was to blame for it?
"Many scenarios had been run prior to Katrina years ago, and with that type of storm, the scenarios should have been taken seriously," Gregory Stone, a professor at the coastal studies institute at Louisiana State University, told BBC World Service's Assignment programme.
"Some of the actions of the mayor, and even the governor of Louisiana, were highly questionable.
"I don't think that the people that have to make these very difficult decisions realised the magnitude of this particular event, which is frustrating for people like me, because we're very much involved in forecasting.
"We'd been telling people all over the world that New Orleans was a nightmare waiting to happen, and certainly, someone at the state level and the local level have got to be held responsible for that."
The Superdome, once the pride of New Orleans, became a symbol of the city's shame when the many thousands of people who could not escape the storm crammed in.
A great many of them believe they were let down by their government, at local and state level, and were left there without food, water, medical help, transport out or security. It is those failings that Governor Kathleen Blanco and Mayor Ray Nagin will have to answer for.
Mr Nagin in particular is accused by some of spending much of the time before Katrina hit trying to work out the legalities of whether he could order a mandatory evacuation, rather than simply ordering people out of the city.
"I think, in many cases what we're dealing with is just multiple levels of incompetence," said one man, a computer consultant who had been inside the Superdome.
"Also, certain inefficiencies - our constitution is designed, in some ways, to almost produce certain inefficiencies in situations like this."
He also said it had been "the longest time" before he had seen a police car, and that at first help was coming from the Salvation Army.
Speaking before he resigned, the former New Orleans police chief, Eddie Compass, told Assignment that the police did "everything humanly possible."
"We could have had some high water vehicles, that would have helped tremendously," he added, but would not be drawn into the question of what lessons should be learned, or whether the emergency plan worked as well as it could have.
"That's something that the politicians are going to have to deal with... I did what I was supposed to. And I am not a politician, I'm the chief of police, and that's all I ever wanted to be," he added.
Mayor Nagin pointed out that actions he ordered, such as getting people to check on others that relied on them, and getting churches to "buddy up," had "hopefully minimised some deaths".
But he also admitted that he "probably could have done some things better than what I did".
"We probably evacuated more people during this storm than ever before in the history of this city," he said.
The Superdome was under prepared for the numbers inside
"Could we have done better? Yes."
Meanwhile, he also said that an analysis and update of the emergency plan was currently under way.
Aaron Broussard, the president of Jefferson Parish - which makes up around a third of metropolitan New Orleans - said that the key failing of the emergency plan was a lack of communication that resulted from the hurricane.
"Mother Nature humbled us," he said.
"We thought we had just arrived at a Star Trek level of communication, and Mother Nature, in three hours, took us from the Jetsons to the Flintstones. We all became yabba-dabba-do people, writing things down on paper, and telling people to go and scout a location, eyeball it, come back and tell me what you see. We had no communication."
He admitted he felt let down.
"If you have knowledge of a problem, and you articulate it well, and you tell everybody about it, and then nobody listens, nobody treats it as a priority - don't you think that is just a sense of helplessness and abandonment?"
"Of course you feel like that. Everybody here feels like that right now."
Governor Blanco was unavailable to talk to Assignment.
But some officials at the Louisiana office of Homeland Security and Emergency Preparedness have two different views of Governor Blanco. While in public they defend her, in private, many are very critical.
One senior official accused her of playing politics throughout the emergency. Another told Assignment that he thought she and her staff had mishandled the crisis from the very start.
But Mark Smith, the spokesman for the Louisiana Office of Homeland Security and Emergency Preparedness - the body which drew up the Governor's plans, and which is co-ordinating the state's response for her - said that as the storm approached, his office had felt "sure that we were okay in our preparedness."
Many buses that could have evacuated people were left on lower ground
But he said that in planning, they had not figured the number of people who would be left behind - "either by lack of resources or by them simply ignoring requests, pleas and cries for them to evacuate."
There had been other problems regarding evacuation, such as sorting out buses. The city of New Orleans - Mayor Nagin's office - had not requested any, he said, making evacuation much more difficult.
But, Mr Smith, he added that "Governor Blanco said quite sometime back that she accepts full responsibility".
"Were we ready for it? In retrospect? Probably not as well as we should have been."