f the state of Oklahoma gets its way, Thomas Lee (Sonny) Hays will make history here. He will be the first man in the world to be legally executed by a lethal injection of drugs.

On the night of his execution, he will be taken from a small, suicide-proof isolation cell at the Oklahoma State Penitentiary and offered a sedative. Then a group of five correctional officers will strap him to a stretcher and hold him down while a medical technician tries to insert a needle into his vein.

No nurse or doctor will be allowed to directly participate in the event--except to declare him dead. It would violate their professional ethics.

Once the intravenous tubes are in place, Hays will be wheeled to the execution room and the ends of the tubing put through a window covered by a curtain.

The executioner--and two standbys--will stand behind the curtain. A clear solution of sodium or dextrose will begin to run into his vein.

At 11:30 p.m., members of the news media will be brought into the viewing room, followed by the family members and legal, correctional and medical personnel that are required by law to attend.

At 12:15 a.m. the curtain between the execution room and the viewing room will be opened and the public address system between the two rooms will be turned on.

Hays will hear his crime and sentence read, and will be given a chance for any last words he cares to speak. Then he will be offered a blindfold.

The execution is scheduled for 12:30 a.m., a holdover from the days of the electric chair when prison officials were worried about overloading the system and knocking out electrical power in the town of McAlester.

At that point, the executioner will shoot thiopental sodium, commercially known as sodium pentothal, into the tubing, and Hays should go to sleep. Then, the executioner will open the valve to a container holding the paralyzing drug curare.

No one knows just how long it will take for Hays to die.

In fact, no one knows whether the process will work. It has never been tried before.

No one knows what will happen if the sedative wears off before the curare does its work, if the dosages are not correct, if the technician misses the vein.

Proponents of the untried procedure claim not only that it will be more humane, but also that it is considerably cheaper than building a gas chamber or fixing up "Old Sparky," the state electric chair that performed 83 executions between 1915 and 1966.

No date has been set for Hays' execution, as lawyers struggle to head it off. Three other states, Texas, Idaho and New Mexico, already have approved executions by lethal injection, and dozens of other states are considering the measure as a method of saving money. Thirty-nine states have death penalty laws, and there are more than 850 prisoners awaiting execution.

The only major study of execution by injection was done about 30 years go by the British, who rejected the method as "impractical."

Lawyers David Kendall and Stephen Kristovich, both of the District of Columbia, have filed suit asking the government to postpone the executions and order the Food and Drug Administration to verify the safety and effectiveness of the drugs.

They argue that death by lethal injection could be slower and more agonizing than electrocution.

It all started out simply enough, a small town robbery run out of control. When it was over, Everett Leonard Vance, 45, lay dead in his Muskogee shoe store, two bullets in his head. Sonny Hays, who had lived in the town all his life and shopped at the shoe store, was convicted of the crime and sentenced to death.

March 9, 1977. Hays, then 40 years old, had been drinking vodka much of the day, but there was nothing new about that. It was a problem that had plagued him since he had come home from the service more than 20 years before.

It was not a happy time in his life. His 42-year-old sister, Patsy, had just died of emphysema and his father was in the hospital dying of cancer.

He had been married at least six times, with many more girlfriends in between, and had virtually lost contact with his only child. He had just decided to reconcile with his most recent wife. But police say that the day of the murder, she had filed a complaint against him, charging he had threatened her that morning with a gun.

Except for the several months he spent in prison in 1959 because of what family members call a "misunderstanding" over a friend's movie camera, Hays had never had a major problem with the law--other than a number of arrests for drunk and disorderly conduct.

But Mike Turpen, the district attorney who prosecuted the case, said Hays was well known to local law enforcement officers. "He was a decent sort of fellow," Turpen said. "Sonny Hays was a police character, the kind of guy who would come into the DA's office and plea bargain for his friends."

Turpen also called Hays a "Jekyll and Hyde character. His friends say he was a pill popper. They say he beat up on his women and friends when he was using them."

All his life, Hays had worked at a series of jobs: mechanic, carpenter, steel work, general construction work, whatever he could get. Friends say he had been paid the day before the murder and planned to use the money to buy groceries and a new pair of boots and to pay the rent.

As family members remember it, Hays' parents had visited his apartment about 5 p.m. that day and stayed with their son and his estranged wife, Erlene Hays, for about 10 minutes before they went home for a quick dinner.

It would be another two hours before Vance's family would find his body on the floor of the shoe store and a trail of circumstantial evidence would lead police to Hays.

Vance's wife testified that her husband was still alive at 5:10 p.m. when he called home to say he would be working late.

Other witnesses placed Hays downtown at about 5:15 p.m. being turned away from two bars, one of them 180 feet from the shoe store.

By 5:30 Hays, appearing intoxicated and carrying a brown paper bag, staggered across an intersection into the path of a car. The three teen-aged boys in the car testified that Hays had reached into the bag, pulled out a gun and waved it at them after they shouted insulting remarks at him. They sped away, ignoring the red light.

A policeman at the same intersection did not see the gun, but followed him from the intersection.

Trying to elude the police officer, Hays crossed along the edge of a service station about the same time as the owner looked out the window and saw a man toss a dark object into the back of a truck parked on his lot.

A short distance away, Hays was arrested on a charge of public drunkenness, and police found that his bag contained a pair of old cowboy boots and $110 in loose bills. In his pockets police found two packs of cigarettes and two lighters.

As Hays was being arrested, the service station owner told police that Hays had thrown something--he believed it might have been a liquor bottle--into the back of the truck. But when they retrieved the object, it was a .38-cal. Llama revolver containing one empty chamber, two spent cartridges and three live rounds.

Vance's body was discovered at 7:30 p.m. About an hour later, as suspicion turned toward Hays, police returned to the service station and in the top of a trash can, about 20 feet from where the gun was found, they discovered two more pairs of boots with the price tags still on them. Later they discovered that one of the lighters and one package of cigarettes had belonged to Vance.

Just over three months later, Hays, who still says he is innocent, was convicted of the murder and sentenced to death.

Today, more than four years after the murder, the case seems further from resolution than ever before.

Despite the mountains of circumstantial evidence, there are problems with Hays' case:

* He was never given a blood test although he had been drinking heavily before the murder and had been picked up for public drunkenness. His drunkenness was never brought up as a mitigating circumstance in the murder.

* He was never given a paraffin test to determine whether he had recently fired a gun, and the prosecutor failed to produce the fingerprint evidence from the store's cash drawer.

* His lawyer raised no objection to the fact that every member of the jury had no philosophical problem with the death penalty.

* There was no effort at an insanity defense--Hays has never been given a formal psychiatric evaluation--even though he had been involuntarily committed to mental hospitals four times before the murder and was later diagnosed in prison in 1978 as a paranoid schizophrenic.

* There is the question of Hays' appeal. A number of Oklahoma lawyers believe the state's death penalty is arbitrary and unconstitutional and that it will be overturned by the Supreme Court when it gets to that level. But Hays' case was never appealed that far.

After Hays lost his first appeal, he never bothered to answer letters from his lawyer asking whether to continue the appeal to the Supreme Court. After the six-month eligibility period had expired, the lawyer went to see Hays. William Settle of Muskogee, the court-appointed lawyer, told the court that Hays had requested an execution date "as soon as possible."

Last May, a state judge concluded after attempting to question Hays that he had not waived his right to appeal. But the federal court went forward and set an execution date of Sept. 14, which would probably have been carried out except for a last-minute postponement obtained by two young lawyers who entered the case two months ago for a $1 fee on behalf of Hays' mother.

Kent Eldridge and Charles F. Cox are asking a federal appeals court to declare Hays mentally incompetent so that they can officially take over the case. If that succeeds, they will appeal his conviction not only on grounds of competency but also on the basis that he received an unfair trial because his court-appointed lawyer did not do an adequate job.

If they fail to convince the court that Hays is mentally incompetent, he is expected to be executed quickly. Since he is not actively fighting the execution, there is nothing to stand in the way.

Alton Franks has known Sonny Hays for about 3 1/2 years. They are two of the 38 inmates who spend their days in small cage-like cells lined up behind the sign that reads "Death Row."

Franks said Hays is "nutty as a fruit cake. Sonny Hays has been crazy since I've been here. Sometimes he won't talk to you for six months. Sometimes he'll go out to the yard and cuss God. Sometimes he throws his clothes out, stands there is his cell naked with a blindfold around his eyes. He can't see anybody, so he figures they can't see him.

"He has his good days and his bad days. But when he goes into one of them moods, it might last a month, two months, one time it lasted a year," he said. "I don't mean he's a blathering idiot. But the man's just not right."

Franks said there were times when he and the others on death row would try to feed Hays, when they tried to convince him to appeal to the Supreme Court, but without much success. Besides their concern for Hays, they're afraid that his could be the first of a wave of executions by lethal injection, that the public will find that method less gruesome and easier to accept. They feel they could be the next to go.

Family members say they first noticed that something was wrong with Hays in the mid-1950s when he came home after serving with the Army in Germany.

He had begun to drink heavily and was getting into fights, even becoming violent with his family and girlfriends.

He complained of odd pains and sometimes coughed up blood. But the one time his parents borrowed the money to send him to a specialist in Tulsa, Hays instead took the money and went drinking.

There were a number of violent incidents. One day he attacked and demolished his mother's sewing machine, claiming that it was trying to kill his father.

Court records show that between 1967 and 1974 Hays was committed to mental hospitals four times because of delusions and violent behavior generally related to his alcoholism.

But Hays never received any systematic psychiatric care at the prison, and there are reports of suicide attempts and long periods when he would remain mute, refusing to speak to anyone. Although he has a high school education, Hays has refused to read or write anything since he went to prison.

By January of this year, another prison doctor discovered that Hays was apparently trying to starve himself to death. He had stopped eating, shaving or showering. He was put briefly in the prison infirmary but not given any sort of psychiatric care.

More recently, Hays has insisted to anyone willing to listen to him that he is God. And for the last four months--until last week--he refused to speak to his lawyers or family members.

Last week, he agreed to speak to an outside psychologist arranged for by Cox and Eldridge. Richard Sternoff, the psychologist, concluded, "My clinical impression would be of a chronic schizophrenic process associated with an organic brain disfunction secondary to alcoholism. In a word, he is not competent."

And for the first time since his appeal was turned down, Hays told him that he might be interested in having the court appoint a lawyer to continue his appeal.

But people who have known Hays say death might be better than spending his life at McAlester, the state's most dangerous prison. It is a place of cold metal bars, murders and homosexual rapes. Turpen calls it the "McAlester Museum of Horrors."

Nancy Nunnally, a spokesman for the Oklahoma Corrections Department, explains that the state decided to switch to lethal injections for "humane" reasons.

"People don't realize it, but the electric chair can take 11 minutes to kill people. The first shock knocks you unconscious, but then it would just cook you. You would literally fry."

But lawyer David Kendall insists that since the method had never been tried, Oklahoma may be on the verge of getting involved in something much more gruesome than electrocution.

"If you manufacture drugs to put animals to sleep, they are tested by the FDA," he said. "We're trying to make sure the FDA treats humans the way it does dogs when it comes to human destruction."

Although the Oklahoma legislature may have adopted the lethal injection statute for humanitarian reasons, economics played no small part in their deliberations.

It was prominently pointed out that it would cost more than $200,000 to build a gas chamber, $60,000 to repair the electric chair. And then there would be maintenance costs on top of that. Death by injection, on the other hand, costs only $10 to $15 "per event."

In his request for an FDA review of the drugs, Kendall points out the number of things that could go wrong.

To begin with, he has expert testimony indicating that sodium pentothal and the curare counteract one another, which could leave Hays awake and gasping for breath until he finally loses consciousness.

In addition, the study conducted by the British three decades ago concluded that it can be extremely difficult to get an intravenous needle into a person, especially if the person is struggling or frightened.

The report found that it is difficult to find veins in certain categories of people, including those who are overweight, who have a history of diabetes or drug abuse and who have darkly pigmented skin. To make matters even more difficult, veins constrict when a person is nervous.

The report concludes that the person to be executed can experience considerable pain if the needle misses the vein and the curare is injected into the surrounding tissue. Kendall outlines a worst-case possibility of the needle missing the vein and being inserted into an artery by mistake, "causing the artery to constrict and the surrounding tissue to die, often with extensive gangrene, and always with excruciating pain to the recipient."

Kendall points out that the drug is unlikely to work if it is injected into an artery, a possibility that is magnified because most medical personnel cannot participate in an execution.

Nunnally said the corrections department plans to use a medical technician who is skilled at inserting intravenous needles and that there is no shortage of volunteers.

Cox and Eldridge are charging that Settle was incompetent in his defense of Hays.

Settle, who said he believes Hays is innocent despite the circumstantial evidence, has taken their criticism calmly. "It doesn't bother me," he said. "They have two chances to win. One is to prove that Sonny is incompetent. The other is to prove his lawyer was incompetent. They're doing their best to keep him alive."

One of the major complaints about Settle was that he accepted a jury that unanimously favored the concept of the death penalty.

Settle said there are still aspects of the trial that bother him, including the failure to conduct a paraffin test and the lack of fingerprint evidence.

But Turpen, who prosecuted Hays, called Settle "one of the best attorneys in Muskogee County."

He said that in a place like Oklahoma the police never conduct paraffin tests or take fingerprints.

"I've never had a paraffin test. You know how many cases I've prosecuted with fingerprints in seven years? None! I'm telling you, that's TV stuff. I don't have anyone who knows how to run a paraffin test.

"Is [the death penalty] barbaric? Is it animalistic? Of course it is. But what about the part people aren't talking about? What about Vance, who grew up in this town and married his high school sweetheart and spent 20 years as an Air Force officer and comes back to open a little shoe store and gets gunned down in broad daylight?" he asked.

"What about his wife and his little 12-year-old daughter who found him lying in a pool of blood? What about the victims?"