According to Memorial workers on the second floor, about a dozen patients who were designated as “3’s” remained in the lobby by the A.T.M. Other Memorial patients were being evacuated with help from volunteers and medical staff, including Bryant King. Around noon, King told me, he saw Anna Pou holding a handful of syringes and telling a patient near the A.T.M., “I’m going to give you something to make you feel better.” King remembered an earlier conversation with a colleague who, after speaking with Mulderick and Pou, asked him what he thought of hastening patients’ deaths. That was not a doctor’s job, he replied. Patients were hot and uncomfortable, and a few might be terminally ill, but he didn’t think they were in the kind of pain that calls for sedation, let alone mercy killing. When he saw Pou with the syringes, he assumed she was doing just that and said to anyone within earshot: “I’m getting out of here. This is crazy!” King grabbed his bag and stormed downstairs to get on a boat.

Bill Armington, the neuroradiologist, watched King go and was upset at him for leaving. Armington suspected that euthanasia might occur, in part, he told me, because Cook told him earlier that there had been a discussion of “things that only doctors talk about.” Armington headed for the helipad, “stirred up,” as he recalls, “to intensify my efforts to get people off the roof.” Neither Armington nor King intervened directly, though King had earlier sent out text messages to friends and family asking them to tell the media that doctors were discussing giving medication to dying patients to help accelerate their deaths. King told me that he didn’t think his opinion, which hadn’t mattered when he argued against turning away the hospital’s neighbors, would have mattered.

ONLY A FEW nurses and three doctors remained on the second floor: Pou; a young internist named Kathleen Fournier; and John Thiele, a 53-year-old pulmonologist, who had never before spoken publicly about his Katrina experiences until we had two lengthy interviews in the last year. Thiele told me that on Thursday morning, he saw Susan Mulderick walking out of the emergency room. “John, everybody has to be out of here tonight,” he said she told him. He said René Goux told him the same thing. Mulderick, through her lawyer, and Goux both say that they were not given a deadline to empty the hospital and that their goal was to focus their exhausted colleagues on the evacuation. “We’d experienced the helicopters’ stopping flying to us,” Goux told me, “and I didn’t want that to occur again.”

Around a corner from where the patients lay on the second floor, Thiele and Fournier struggled to euthanize two cats whose owners brought them to the hospital and were forced to leave them behind. Thiele trained a needle toward the heart of a clawing cat held by Fournier, he told me later. While they were working, Thiele recalls Fournier telling him that Mulderick had spoken with her about something to the effect of putting patients “out of their misery” and that she did not want to participate. (Fournier declined to talk with me.) Thiele told her that he understood, and that he and others would handle it. Mulderick’s lawyer says that Mulderick did ask a physician about giving something to patients to “make them more comfortable,” but that, however, was not “code for euthanasia.”

Image THE HELIPAD AUG. 1, 2009 Many patients were evacuated by helicopter off the top of the eight-story parking deck next to the hospital. Credit... Paolo Pellegrin/ Magnum , for The New York Times

Thiele didn’t know Pou by name, but she looked to him like the physician in charge on the second floor. He told me that Pou told him that the Category 3 patients were not going to be moved. He said he thought they appeared close to death and would not have survived an evacuation. He was terrified, he said, of what would happen to them if they were left behind. He expected that the people firing guns into the chaos of New Orleans — “the animals,” he called them — would storm the hospital, looking for drugs after everyone else was gone. “I figured, What would they do, these crazy black people who think they’ve been oppressed for all these years by white people? I mean if they’re capable of shooting at somebody, why are they not capable of raping them or, or, you know, dismembering them? What’s to prevent them from doing things like that?”

The laws of man had broken down, Thiele concluded, and only the laws of God applied.

“Can I help you?” he says he asked Pou several times.