Minutes past midnight last Aug. 31, surgeon Kenneth R. Smith watched from behind glass in a Missouri prison as convicted murderer George C. Gilmore, strapped to a gurney with an intravenous line in his arm, was put to death by lethal injection.

Less than eight hours later, Smith walked into the operating room at St. Louis University Medical Center where he is chairman of neurosurgery.

What struck him was the eerie similarity between the two scenes.

"It looks the same," said Smith, who had driven the 150-mile round trip in one night to be an official witness at Gilmore's ex- ecution. What he saw in both rooms was a person lying on the operating table, connected to a heart monitor and IV lines, with anesthetic drugs going in.

"The only difference," Smith said of Gilmore's execution, "was that afterward, instead of going to the recovery room, he went to the hearse."

Perhaps not since a French physician named Joseph Guillotin promoted his painless, quick and "democratic" method of beheading criminals 200 years ago has the medical profession been at such pains to distance itself from capital punishment. (Guillotin's killing machine was perfected by a French surgeon, Antoine Louis, who redesigned the slanted blade to make a cleaner cut.)

The latest refinement of execution has occurred in the past decade: lethal injection. In keeping with the history of capital punishment, lethal injection is hailed by proponents as a technological advance, more humane and less barbaric than its predecessors such as the electric chair and the gas chamber -- which in the past century were touted as improvements on the gallows.

"It's cleaner and more painless," said Donald R. Schroeger, spokesman for the Missouri Department of Corrections, which gave up its gas chamber in favor of lethal injection in 1988.

More than half of the 36 states where capital punishment is legal now specify lethal injection. Its political appeal among state legislators who favor the death penalty is two-fold. Lethal injection is seen as more humane than other methods of execution and is believed to be more palatable to juries voting in capital cases.

But lethal injection, too, has proved controversial. Critics say it is an effort to "sugarcoat" legalized state killing, with a disturbing resemblance to the horrific scientific "experiments" on death camp prisoners carried out by Nazi doctors. Particularly unsettling to many physicians -- including some who support the death penalty -- is the fact that lethal injection is based on what doctors call "the medical model," consisting of massive overdoses of anesthetics dripped into the bloodstream through an intravenous tube.

Unlike other methods of execution, lethal injection looks much like the kind of medical treatment thousands of patients receive every day in hospitals around the country.

"Nobody would ever confuse a guillotine with medical therapy," said Richard L. Keenan, chairman of anesthesiology at the Medical College of Virginia in Richmond. "But I'm an anesthesiologist, these are my tools. The very drugs are the ones we use every day in the operating room."

In a lethal injection, the condemned inmate is strapped onto a hospital gurney and wheeled into the execution room. A trained technician -- usually not a doctor -- inserts a needle into a vein in the inmate's arm and begins an intravenous flow of saline solution.

At the warden's signal, a lethal combination of drugs is injected into the IV line. The deadly concoction typically includes three drugs: a nonlethal dose of sodium thiopental, a sleep-inducing barbiturate, and lethal doses of pancuronium bromide, a drug that paralyzes the muscles, and potassium chloride, which stops the heart within seconds. The first two drugs are commonly used during surgery to put the patient to sleep and relax muscles; the third is used in heart bypass surgery.

The political attraction of lethal injection is rooted in Americans' ambivalence about the death penalty, said neurosurgeon Smith. "We're trying to kill somebody without anybody being responsible for it," he said. "We want to kill him, but we want to do it quietly in a 'kind and humane' way -- and make it look like a surgical operation so nobody will complain much."

With an all-time high of nearly 2,400 Americans living on Death Row, capital punishment remains one of the most acrimonious issues in American politics. Both proponents and opponents are uneasy with the debate over how -- or whether -- the death penalty can be made humane.

Those who oppose capital punishment on principle are at pains to emphasize that calling one method more "humane" than another does not undercut their fundamental belief that all state-ordered killing is barbaric. On the other hand, few proponents of capital punishment are enthusiastic about debating the merits of various methods of execution.

For doctors, the very aspects of lethal injection that prompt legislators and other public officials to endorse it are what make it ethically troubling. "It is a more obvious application of biomedical knowledge and skills than any other method of execution yet adopted by any other nation in modern history," warned cardiologist Ward Casscells and lawyer William J. Curran in the New England Journal of Medicine in 1980, nearly three years before the first execution by lethal injection.

"It has the gloss of being nice and clinical and humane," said Jerry Gorman, a family practice physician in Richmond. "But we're using the medical model -- which is supposed to be healing and nurturing and restorative -- deliberately to kill a prisoner."

Does the use of medical instruments, drugs and techniques to kill a person in a court-ordered execution violate medicine's code of ethics and the basic principle of the Hippocratic Oath: "First, do no harm"? Can a doctor ethically participate in such an execution? What is participation? Injecting the lethal mixture? Inserting the catheter? Examining the inmate's veins beforehand? Checking vital signs during or afterward? Pronouncing the victim dead?

Where does medicine draw the line? Straddling an Ethical Fence

Last week, amid growing concern about the possible involvement of physicians in capital punishment, the American Medical Association reiterated an ethical line it drew for its members in 1982, a few months before the nation's first execution by lethal injection.

"A physician, as a member of a profession dedicated to preserving life when there is hope of doing so, should not be a participant in a legally authorized execution," the AMA had declared. "A physician may make a determination or certification of death as currently provided by law in any situation."

In other words, the doctor's only ethical role in an execution is to pronounce the victim dead.

"Pronouncing a patient dead is clearly a limited function," said Nancy W. Dickey, a family physician in Houston who chaired the AMA's Council on Judicial and Ethical Affairs.

"Physicians pronounce a patient dead at the scene of an auto accident without participating in the accident," said Dickey, an AMA trustee. "Asking a physician to stand by and suggest more medicine or more electricity {during an execution} is a different matter."

But Dickey is not comfortable with the trend toward lethal injection. "Personally, I have concerns about using a medical technique for the purposes of execution," said Dickey, emphasizing that she was speaking for herself and not for the AMA. "That blurs a line that is so easily blurred anyway.

"Medical technology should be used to relieve suffering and return people to better health. Obviously this {lethal injection} is subverting it for something totally different."

The first American execution by lethal injection took place in 1982 in a brick-walled death chamber in the Texas state prison in Huntsville -- the same room where 361 prisoners had died in the electric chair. Technicians injected a lethal overdose into the intravenous lines leading through an opening in the wall to the inmate's arm.

Surgeon Ralph Gray was one month from retirement as medical director of the Texas prison system when he witnessed that first lethal injection eight years ago. Gray observed while three technicians -- none a physician -- repeatedly missed the arm veins of convicted murderer Charles Brooks Jr. and blood spattered the sheet.

"I could have hit those veins easier than the people who did it," Gray told the AMA News, "but I said there was no way I was going to get involved."

Gray had been sharply criticized for earlier examining the veins in Brooks's arms -- a step he defended by saying that Brooks' veins were weakened by years of drug use and that one of the technicians had not started an IV in years. "I really don't see what I did wrong. I wanted things to go properly," he said.

A few minutes after the lethal injection began, Gray checked Brooks' eyes and listened to the chest. He waited for the pops and crackles in the lungs to cease, then checked the widely dilated eyes again. Then he pronounced Brooks dead. The procedure took seven minutes.

Limiting Doctors' Role

Since the AMA forbade physician participation in the death penalty and Charles Brooks became the first American executed by lethal injection, state prisons have gone to extraordinary lengths to distance their medical staffs from direct involvement in such executions.

In Oklahoma, the first state to adopt lethal injection, a physician is no longer required to check the catheter in the condemned prisoner's vein.

The doctor in attendance at Missouri executions monitors the dying person's electrocardiogram from behind a screen, anonymous and out of sight of the official witnesses.

In Utah, two executioners, neither one a doctor or nurse, inject identical-looking prepared units of drugs into a Y-shaped IV line; one unit is lethal and the other harmless. Neither executioner knows which is which.

In Texas, where 37 lethal injections have been carried out, the physician stands outside a closed door and enters the execution room only after the warden signals that it is time to pronounce the prisoner dead.

No doctor's prescription is needed for the drugs. By law, a prison warden can sign for them. Nor do prison physicians prepare or administer the lethal mixture of drugs. Technicians -- or in the bureaucratic language most states have adopted, "medically qualified personnel" -- do that.

Sometimes, as in Missouri, the injection is done by a machine. Missouri bought a $40,000 lethal injection machine two years ago after tests with a smoke bomb revealed a leak in the seal around the state's gas chamber. The machine has six syringes activated by mechanical plungers. Three syringes hold lethal drugs; the other three contain harmless solution. Two buttons control the machine, one for the lethal syringes and one for the identical-looking harmless ones.

"The two executioners each press a button, and the syringes release the drugs into the IV line," said Missouri Corrections spokesman Schroeger. "Neither one knows which one is actually the executioner. The machine actually administers the drugs."

It's the moral equivalent of the "blank" in the firing squad. When convicted killer Gary Gilmore was shot to death by a five-member firing squad in Utah in 1977, four rifles contained live rounds and one a blank. Theoretically, that ritual preserves the anonymity of the actual executioners.

But defining the limits of medical participation in lethal injection is more difficult. Even in states that use machines, such as Missouri and Illinois, someone has to insert the IV line into the condemned inmate's arm before the machine releases the drugs.

Last year, in Missouri's first lethal injection, a physician inserted the IV line, Schroeger said. But prison officials changed the policy, and IV lines are now inserted by nondoctors, he said. "The physician only monitors the machine and certifies death."

An Illinois prison warden touched off a furor last September when he enlisted three unidentified physicians to insert an IV line into the arm of condemned killer Charles Walker in preparation for the state's first lethal injection. Medical organizations protested to no avail, and several lawsuits challenged the state's regulations, which call for a "licensed physician, RN {registered nurse} or physician extender" {technician qualified in medical procedures} to insert the catheter.

Lethal injection has prompted other unforeseen legal challenges. In Washington state, where the law gives condemned inmates a choice of hanging or lethal injection, convicted murderer Charles Campbell has filed a lawsuit claiming it is "cruel and unusual punishment" to be forced to choose the method of one's demise. In the early 1980s, a group of Death Row inmates sued to ban use of lethal drugs in capital punishment on the ground that the Food and Drug Administration had not approved them for that use. The case went all the way to the Supreme Court, which in 1985 ruled unanimously against the inmates. Justice William H. Rehnquist said it was "implausible" to require drugs used in executions to meet the FDA's "safe and effective" test.

Unexpected Effects

Botched executions are much less common than in the days when hanging was the usual practice, but no method is totally reliable. A 17-year-old convicted killer named Willie Francis survived an attempted electrocution in the Louisiana electric chair in 1946. He was sent back to his cell and, after losing an appeal to the Supreme Court, was executed the next year.

More recently, during the electrocution of Jesse Joseph Tafero last May in Florida, a synthetic sponge in the headpiece caught fire and flames erupted from his shaved head.

The latest execution in Virginia's electric chair also was controversial. Wilbert Lee Evans was put to death Oct. 17 for shooting an Alexandria sheriff's deputy during an escape attempt in 1981. After the first of two surges of 2,400 volts, Evans's body lunged forward and blood poured from under the leather mask, soaking his shirt. Prison Chaplain Rev. Russell Ford, who has witnessed six executions, called this one "unique." He described Evans as "covered in blood" and said air was being forced out of his mouth with a noise "somewhat like the sound a pressure cooker makes." After a second jolt of electricity, Evans's body went limp, and he was pronounced dead.

State Corrections Director Edward W. Murray said after the execution that nothing went wrong. "The man just simply had a nosebleed," he told reporters. He attributed the bleeding to Evans's high blood pressure.

"People should not be surprised by blood at an execution," said Richmond physician Gorman, who withholds a penny from his electric bill every month as a protest against Virginia's electrocutions. "When you put people to death, nasty things happen. The only malfunction of the Virginia chair would be if the person survived."

Nor is lethal injection error-proof.

In 1985, when Stephen Peter Morin was executed by lethal injection in Texas, technicians took nearly 45 minutes to find a vein; Morin's veins had deteriorated from years of drug abuse. The next year, Randy Woolls, a drug addict, had to help technicians find a usable vein for his execution.

Two years ago, two minutes into the execution of Raymond Landry in Texas, the catheter popped out of the vein in his arm, leaking onto the floor. Officials pulled a curtain in front of witnesses for 14 minutes until technicians could reinsert the tube into Landry's vein and resume the procedure.

Medical College of Virginia's Keenan is not opposed to capital punishment in general. But as an anesthesiologist, he said lethal injection is "very dangerous" to public confidence in doctors and "sends the wrong message" to patients. "My own personal view," Keenan said, "is that some other form of death, such as electrocution, would be more appropriate because it could not be mistaken for medical therapy."

"I can see the appeal of it -- putting him to sleep rather than blowing his head off, or whatever," he added. "But I'd argue it isn't going to reduce the anxiety."

None of the euphemisms and elaborate procedures -- one-way windows, physicians out of sight, double or triple IV lines, anonymous technicians -- can obscure, Keenan said, what is really going on: "All the while the prisoner is there, wide awake and looking at them."

Appearances aside, Keenan said, lethal injection is no more humane and certainly no quicker than electrocution. Loss of consciousness is instantaneous in an electric chair, no matter how gruesome it looks -- and even if "signs of life" such as breathing and heartbeat continue for several minutes.

"With the first jolt of electricity, all the brain cells are depolarized," Keenan said. "They just turn off, and the prisoner is completely unaware of anything after that first instant."

"When people say lethal injection is more humane," said family physician Gorman, "they mean to the witnesses, not to the prisoner."

Whatever the reason, lethal injection has growing support among advocates of capital punishment. Even critics acknowledge that it has changed the nature of the death penalty.

"Lethal injection has been merchandised -- and successfully so -- as being more efficient, more technological, more humane, safer and less expensive," said Henry Schwarzschild, director of the capital punishment project of the American Civil Liberties Union, which opposes the death penalty. But the real purpose -- and effect -- is "to facilitate executions," he said.

"Psychically, it works very well," Schwarzschild said. "You and I could go around to the Death Rows and ask the inmates how they would have it done and they might choose lethal injection.

"You and I might, too, for all I know."