For Louisiana alone, the toll surged by more than half to 423, and officials fear the numbers could climb as floodwaters recede and more of the city becomes accessible to search teams.
Including deaths in four other states, Katrina's overall death toll stood at 659.
Authorities said the toll would be lower if Salvador and Mable Mangano, owners of the St Rita's nursing home, Chalmette, had heeded warnings to evacuate their patients as Katrina came ashore on August 29.
"The pathetic thing in this case was that they were asked if they wanted to move them and they did not," said Louisiana Attorney General Charles Foti. "They were warned repeatedly that this storm was coming. In effect, their inaction resulted in the deaths of these people."
The Manganos were released on $50,000 bond each; each of the 34 counts against them carries up to five years in prison.
Their attorney Jim Cobb said his clients were innocent and had waited for a mandatory evacuation order from the officials of St Bernard Parish that never came.
Cobb said the Manganos were forced to make a difficult decision: risk the health of the patients many of them frail and on feeding tubes in an evacuation, or keep them comfortable at the home through the storm.
Tom Rodrigue, whose mother died in the home, was not satisfied. "She deserved the chance to be rescued instead of having to drown like a rat," he said.