Injury on Angel Diaz's right arm

The intended purpose of the thiopental was to make Diaz unconscious. Then the second drug, a paralyzing agent called pancuronium bromide, would shut down Diaz’s control of voluntary muscles. Finally, a third drug, potassium chloride, was supposed to stop his heart. According to an official state review of the execution, a member of the execution team noticed more resistance in the syringe than usual when he or she began to pump thiopental into Diaz’s left arm. This person was able to complete the dosage, and then began to administer pancuronium bromide through the same IV. The resistance grew, however, until the point where he or she could push the plunger no further. The execution team switched to the IV in Diaz’s right arm to complete the dosage of pancuronium bromide and then applied potassium chloride. When it failed to stop Diaz’s heart, the execution team administered another full cycle of the three-drug cocktail, switching back midway from his right arm to his left.

Drugs work differently subcutaneously than they do intravenously. "If thiopental infiltrates, it will not produce anesthesia," said Heath. In previous botched executions, thiopental accidentally administered subcutaneously has failed to knock prisoners unconscious: A few months before Diaz's execution, Joseph Clark, a convicted murderer in Ohio, remained awake after receiving thiopental in a collapsed vein, and executioners had to find a new vein before restarting his execution. And thiopental is the most important drug in the execution, from the prisoner’s perspective: If it fails, he will be awake to feel the torturous effects of the other two drugs. The second drug, pancuronium bromide, paralyzes the prisoner, including his diaphragm and lungs: In clinical settings, patients must be put on ventilators to continue breathing. And pancuronium bromide, unlike thiopental, works even when it’s administered subcutaneously: "Infiltrated pancuronium still accumulates in the circulation in fully effective concentrations, and so the prisoner will become 'chemically locked in' over a period of ten to twenty minutes," said Heath. The third drug, potassium chloride, is known to be painful intravenously. In order to cause cardiac arrest, a single large dose needs to hit the heart through the bloodstream—which we know didn’t happen in Diaz’s case.

In all likelihood, Diaz remained conscious as the drugs pooled in his arms and the pancuronium bromide began to paralyze him. Diaz would have become chemically locked in—that is, mentally aware but without control of any voluntary muscles—and he would have starved for air as his diaphragm shut down and he slowly suffocated. In the autopsy report, the medical examiner noted “bilateral jugular venous distention”—an abnormal swelling of both jugular veins in Diaz’s neck that could be a sign he struggled for air.

Witnesses to the execution reported Diaz moved throughout the procedure, suggesting he was awake and trying to overcome the onset of paralysis. Chris Tisch, a St. Petersburg Times reporter who witnessed the execution, wrote that Diaz immediately began grimacing and appeared to speak at the start (his words could not be heard by the witnesses because a glass window separates the death chamber from the viewing room). He repeatedly squinted his eyes and lifted his chin. Ten minutes into the execution—around the time he was expected to die—he turned his head to the right and began to cough. Sixteen minutes into the execution, he was still moving his mouth and chin. By the twenty-second minute, he appeared to have stopped moving—but then two minutes later his body “jolted,” according to Tisch, and his eyes opened more widely. At 6:34, a doctor checked Diaz’s vital signs. He or she left the execution chamber, returned a minute later, checked again, and at 6:36 an execution team member pronounced Diaz dead.

Tisch wrote in his notes that for several minutes Diaz’s mouth was “flexing like a fish out of water”—a sign he was struggling for air. Ron Word, an Associated Press reporter, also witnessed the execution. Afterwards, he wrote: “It seemed like Angel Nieves Diaz would never die.”

The Florida Department of Corrections originally said that Diaz’s execution took longer than expected because he had liver problems that slowed the chemicals. But the autopsy showed that his liver was healthy. And doctors said even if Diaz did have liver problems, they would have sped up his death rather than slowed down his death.

Two days after Diaz died, Governor Bush put a moratorium on all Florida executions. He also assembled a panel of experts to review and revise Florida’s lethal injection protocol. This panel, which included doctors and state politicians, found that the execution team lacked appropriate training and that the team did not follow the proper protocols. However, it said “it is impossible for the Commission to reach a conclusion as to whether inmate Angel Diaz was in pain.” It made several recommendations to better train the execution team, reinforce the command structure, improve documentation, and monitor more closely the prisoner’s condition. It also recommended the “Florida Department of Corrections on an ongoing basis explore other more recently developed chemicals for use in a lethal injection execution with specific consideration and evaluation of the need of a paralytic drug like pancuronium bromide in an effort to make the lethal injection execution procedure less problematic.” In 2007, Florida’s new governor, Charlie Crist, lifted the moratorium on the death penalty. In a statement, the Florida Department of Corrections noted it had updated the execution protocol since Diaz's execution. "Carrying out the sentence of a court in a capital case is the Florida Department of Corrections’ most solemn duty, and the Department remains committed to doing everything it can to ensure a humane and dignified lethal injection process," the statement read.

After a nationwide shortage in thiopental, Florida replaced the first drug in the three-drug cocktail with midazolam in 2013. Unlike thiopental, which is used in the clinical context to make patients deeply comatose before surgery, doctors typically use midazolam as a sedative to calm patients or to induce amnesia of surgery. Last October, Florida executed its first prisoner with midazolam, a convicted murderer and rapist named William Happ. The Associated Press reporter who witnessed the execution wrote, “It appeared Happ remained conscious longer and made more body movements after losing consciousness than other people executed recently by lethal injection under the old formula.”

Oklahoma also executed Clayton Lockett using midazolam as the first drug—though the dosage was only a fifth of the amount Florida used for Happ. After the botch, Oklahoma said Lockett died from a heart attack. One cause might have been the potassium chloride, though that is unlikely if the drug was not entering his bloodstream. It could have been from something else, such as air entering his vein. It also could just be incorrect, as was Florida’s report of “liver problems” for Angel Diaz immediately after his execution.

After his death, Oklahoma sent Lockett’s body to Dallas for an autopsy; then, at the request of Lockett's legal team, the body was returned to Oklahoma for a second autopsy by an independent forensic pathologist. The results of these autopsies have not yet been released. Unlike Bush, who appointed an independent panel to review Diaz’s execution, Oklahoma Governor Mary Fallin ordered just Michael Thompson, the state commissioner of public safety, to investigate the Lockett execution and recommend changes to the state protocol.

It is important to note that a botched execution would not necessarily cause any physical injuries at all. One of the main concerns with lethal injection is the integrity of the drugs, especially since the shortage in thiopental sent states scrambling for untested replacements. Even if the drugs are administered perfectly through an IV, the prisoner would still suffer if the first drug does not knock him out. “How enviable a quiet death by lethal injection,” Supreme Court Justice Antonin Scalia wrote in 1994, comparing the deaths of executed prisoners to the violent deaths of their victims. In some cases, though, it is the quietness of three-drug lethal injection, inflicted by the paralyzing drug that may have suffocated Angel Diaz, that is most cruel about it.

Corrections: The article originally stated that the drug midazolam is in the narcotics class when, in fact, it is in the benzodiazepines class. The article also originally misstated the order of Lockett's autopsies: His body was sent to Dallas for an autopsy by the Oklahoma state government; it was then returned to Oklahoma at the request of his legal team for a second autopsy.