Dr. Anna Pou thought the horror that followed Hurricane Katrina ended when rescue workers plucked her from the flooded hospital where she rode out the storm and its aftermath.

For almost a week, she dealt with no electricity, 110-degree temperatures and death inside Memorial Medical Center. Looters roamed the streets outside. At least 30 people died at the hospital, many from dehydration while waiting for rescuers.

But for Pou, the horrors of the August 2005 storm did not end until Tuesday, when a grand jury refused to indict her on murder and conspiracy charges.

"Today's events are not a triumph, but a moment of remembrance for those who lost their lives in the storm and a tribute to all of those who stayed at their posts and served people most in need," she said at a news conference.

Pou (pronounced "Poe") and two nurses were arrested last summer after Attorney General Charles Foti concluded they gave "lethal cocktails" to four patients after the storm. Pou acknowledged administering medication to the patients but insisted she did so only to relieve their pain.

Charges against the nurses, Lori Budo and Cheri Landry, were dropped after they were compelled to testify last month before the grand jury under legal guidelines that kept their testimony from being used against them.

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

The grand jury's decision was a defeat for Foti, who accused the doctor and the nurses. The New Orleans district attorney presented the case to the grand jurors and asked them to bring charges.

"We did our job as the law called for us to do," Foti said at a news conference.

He said some of the evidence wasn't presented to the grand jury, but District Attorney Eddie Jordan said he gave the jurors everything he had.

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

Many people in New Orleans believed the three acted heroically under punishing conditions. Last week, a group of doctors and nurses held a rally on the anniversary of Pou's arrest, and hundreds turned out in support.

When the levees broke in New Orleans, 80 percent of the city flooded. The lower level of Memorial Medical Center was under 10 feet of water.

In an interview last fall with CBS' "60 Minutes," Pou stressed: "Anytime you provide pain medicine to anybody, there is a risk. But as I said, my role is to help them through the pain."

Other doctors said the hospital resembled one in the middle of a warzone.

"It was stifling. We were hoisting patients floor-to-floor on the backs of strong young men. It was as bad as you can imagine," Dr. Gregory Vorhoff, who stayed throughout the storm and eventually hitched a ride on a boat to seek help, told The Associated Press after Pou was arrested.

The four patients Pou was accused of killing ranged in age from 61 to 90. Foti said all four would have survived if they had not been given morphine and midazolam hydrochloride.

Autopsies were performed, but the results were not released because of the grand jury investigation.

Many hospitals in the region remain closed or are operating with reduced services nearly two years after Katrina. They also report difficulty in attracting and keeping medical staff.

Pou, whose specialty is eye, ear, nose and throat surgery, gave up her private practice after she was arrested. She has been teaching at LSU medical school in Baton Rouge.

On Tuesday, she said she hoped to resume her practice as soon as possible and urged officials to require that hospitals be evacuated for storms stronger than Category 2.

"It is my hope to return to work doing what I love to do best," she said.

If another hurricane threatened when she was on duty, she would stay to do her job, Pou added. But she is concerned her case will keep other medical professionals from remaining with patients during storms.

"All of us need to remember the magnitude of human suffering that occurred in the city of New Orleans in the wake of Hurricane Katrina so we can be assured that this never happens again and that no health care professional should ever be falsely accused in a rush to judgment," she said.