New Orleans ? A year of impassioned defenses gave way to relief for Dr. Anna Pou on Tuesday when a grand jury refused to indict her, rejecting claims she deliberately gave patients lethal doses of drugs amid the chaos of Hurricane Katrina.

“I fell to my knees and thanked God for helping me,” she said at a news conference, tearfully reading from a prepared statement.

Since last summer, when Attorney General Charles Foti accused Pou and two nurses of killing four patients, many of their colleagues defended them, saying their efforts to ease patients’ pain were not crimes.

On Tuesday, it was Foti’s turn to be defensive.

“We did our job as the law called for us to do,” he said at the news conference, his voice shaking at times before growing angry when a reporter asked about his re-election prospects. “I really don’t care how it affects my chances for election,” he snapped.

The grand jury’s decision closes the books on the only mercy-killing case to emerge from the August 2005 storm, which left Memorial Medical Center flooded and its patients sweltering in 100-degree heat.

Foti said the four patients, ages 61 to 90, would have survived if they had not been given morphine and midazolam hydrochloride. Pou acknowledged administering medication to the patients but insisted she did so only to relieve pain.

It was not Foti but District Attorney Eddie Jordan who presented the evidence to grand jurors, asking it to bring murder and conspiracy charges. Foti said some of the evidence wasn’t presented to the grand jury, but Jordan said he gave them everything he had.

“I feel the grand jury did the right thing,” Jordan said.

Foti said he regretted the jury’s decision, and that five experts independently concluded a homicide had been committed. Although Pou (pronounced “Poe”) was charged in only four deaths, Foti said nine deaths at the hospital appeared suspicious.

“At 11 o’clock on Thursday, Sept. 1, while the hospital was being evacuated both by boats and helicopter, all nine of those people were alive,” he said. “By 5 o’clock, when the last person was moved from the hospital, all nine of those people were dead.”

Pou refused to answer questions about what happened at the hospital because of lawsuits filed by families of three patients.