There are signs in the home that the water rose to the roof. Three inches of muck still cover the floors. Tadpoles wriggle in doorways. The stench is nauseating.

The story of St. Rita's leads locals here to voice the same frustrations they have about the entire disaster.

"Why didn't they evacuate?" Mr. Nunez asked. "Why?"

Mr. Nunez also said, with some bitterness, that his parish got only sporadic help from state and federal authorities.

St. Bernard's Parish has five major nursing homes with roughly 65 patients each, said Henry Rodriguez Jr., the parish president. There are another six smaller facilities, he said. Almost all but St. Rita's were evacuated before the storm.

Steve Kuiper, vice president of operations for Acadian Ambulance, said he was told that St. Rita's had an evacuation plan that depended on another nursing home. Acadian, by far the largest ambulance provider in the state, used helicopters to evacuate many of the parish's neediest medical cases after the storm hit. But Mr. Kuiper said he never heard from St. Rita's.

"They didn't think this would ever happen," Mr. Melerine said. "They just didn't evacuate."

The failure at St. Rita's is particularly difficult to explain. The home is in a depression in the ground. The nearby road, which was covered with four or five feet of water, sits at least five feet above the home's floor. The home appears in retrospect to be particularly vulnerable to flood. Efforts to reach its management late Tuesday were unsuccessful.

Military and private helicopters began ferrying people out of St. Bernard Parish almost as soon as the storm hit. The Coast Guard spent much of the day of the storm landing people on a berm above the Mississippi River near downtown Chalmette, which is some of the highest ground around.