Mark Fowler, a physician with 25 years’ experience, stepped beneath the bright lights and approached the middle-aged man lying on a gurney. Around him, people in medical gowns prepared needles and sterile tubing.

It had all the appearances of a hospital setting.

Fowler had been called in to help establish an IV line through which the 57-year-old man, Tony Carruthers, would be injected with pharmaceutical drugs. The team had struggled to find a vein, so Fowler was summoned to set a central line – an intravenous catheter inserted into the major vein below the collarbone.

First, he had to numb the area where he would cut Carruthers with a scalpel and then pierce the vein with a large needle. But before he applied the lidocaine, he asked the IV team if “the patient” was allergic.

It was a strange choice of words. Carruthers was not a patient, and the room was not an OR.

Fowler had entered the death chamber at Riverbend maximum security prison in Nashville, Tennessee. Carruthers, condemned to death for a triple murder in 1994 for which there was no forensic evidence and over which he has always maintained his innocence, was forcibly strapped to the gurney.

The tube Fowler was attempting to insert would pipe the sedative pentobarbital at a lethally high dose.

Standing just a few feet away inside the chamber was Carruthers’ lawyer, Maria DeLiberato, a senior counsel at the ACLU’s capital punishment project.

She heard the doctor’s description of her client, and recoiled.

“He called Tony ‘the patient’,” she said. “And he was trying to kill him.”

Mark Walton Fowler, 68, of Union City, Tennessee, is an exceedingly rare breed: a doctor who signed up to participate in executions, and whose identity has become public.

In most cases, execution physicians are shielded by ironclad secrecy laws, allowing them to carry out their controversial work shrouded in anonymity.

Fowler has not been so lucky. He was identified, paradoxically, by the Tennessee department of corrections. A warden inadvertently let slip his name as he announced the death by lethal injection of another death row prisoner, Byron Black, 69, last August.

The public disclosure has clearly inconvenienced Fowler. Two months after his name was released, he was subpoenaed by lawyers acting for prisoners challenging the constitutionality of Tennessee’s lethal injection protocol.

In the course of the deposition, an irritated Fowler scolded his inquisitors.

“I certainly hope your office will handle this responsibly,” he chided, “and that I won’t be reading about myself in the Nashville Banner or the Guardian.”

Before Fowler could read about himself in the Guardian, I called him on his cell phone. He declined to respond to a list of detailed questions, but he did say that this was “a private situation. The inmate is entitled to privacy. The lawyers are churning up a lot of nonsense, and I don’t want to discuss it.”

The inconvenient truth, however, is that Fowler’s situation is no longer private. It has erupted into public debate about the death penalty and Tennessee’s record in applying it.

The botched procedure placed Carruthers in his own rare category: people who have survived an execution attempt.

Fowler was unable to secure the central line, and after Carruthers had spent an hour and 15 minutes being repeatedly pierced by Fowler and the IV team in his arms, feet and shoulder, the execution was called off.

Next Thursday, Tennessee is scheduled to execute Darrell Hines also by lethal injection. The prisoner, 65, who was convicted of a 1985 murder, is in poor health, having suffered multiple strokes that have left him partially paralyzed.

Hines’s lawyers have argued in court filings that if Fowler were to be allowed back into the death chamber for what would be his fifth execution, the same botched procedure endured by Carruthers would probably be repeated. They alleged that there would be “an intolerable risk that [Hines] will experience severe suffering due to the … use of insufficiently qualified medical personnel”.

On Thursday, the Tennessee supreme court denied a motion that would have obliged the state to disclose whether the physician will be on duty next week. That means he is now likely to disappear back into the shadows.

At a more fundamental level, Fowler’s unmasking has laid bare the ethical conundrum at the heart of lethal injections, America’s killing technique of choice for the past 44 years. From its inception, the protocol has been wrapped in the swaddling clothes of medicine.

It was billed as the humane answer to the primitive brutality of the electric chair or the firing squad. But to meet such claims, death penalty states have had to persuade doctors to participate – and there’s the rub.

For 2,500 years doctors have operated under the Hippocratic Oath, with its soaring edict: “Do no harm.” The following line of the oath is less well known, but for these purposes even more instructive: “To please no one will I prescribe a deadly drug, nor give advice which may cause his death.”

In 1980, two years before Charles Brooks in Texas became the first prisoner to be killed by lethal injection in the US, the American Medical Association issued a clear prohibition: “A physician must not participate in a legally authorized execution.”

As Corinna Lain has chronicled in her book, Secrets of the Killing State, that has whittled down the field of physicians available to death penalty states to a rump of those Lain calls the “dissenters” – doctors ethically flexible or contrarian enough to bring their white coats and healing arts into the death chamber.

And as we now know from the warden’s slip of the tongue, Fowler is one of them.

The road that led Fowler to Riverbend, Tennessee is long and winding. He studied public administration at the University of Tennessee (UT), then went into law.

Long before he became involved in executions, Fowler spent three years as a public defender. He even represented several capital defendants, managing in each case to persuade the jury to spare his client a death sentence.

Around 1994 Fowler made a dramatic career switch, retraining to become a doctor at the UT Memphis college of medicine. The yearbook of his 1999 graduating class shows him wearing a gown and glasses, smiling broadly. His appearance chimes with the description given by someone who has worked alongside Fowler: “He looks like the kind of fella who goes on fishing trips in Alabama and drinks beer.”

In a quarter century of medical practice Fowler has tried his hand at several different aspects of the profession. For the first decade or so he worked as an ER physician, then as a family doctor. Today, most of his income comes through numerous medical directorships, including of weight loss and aesthetic clinics, and a wound care facility.

There have been controversies along the way. In the deposition he said his employment ended at Centurion, the company that provides healthcare services to Tennessee’s prisons, after he engaged colleagues in a conversation about a transgender prisoner in a women’s prison in Connecticut whom he claimed had impregnated two other women.

We don’t know precisely what Fowler said, but it was provocative enough to inspire a formal complaint from the prison psychiatrist who overheard it.

Fowler writes occasional opinion columns for his local newspaper, the Union City Daily Messenger, that are reproduced by the conservative blog the Patriot Post. The articles give a glimpse into his staunchly rightwing, Trumpian worldview – a way of thinking whose proponents often advocate for the death penalty and have proposed reverting to older, brutal methods such as “firing squads”.

After Renee Good and Alex Pretti were shot dead in Minneapolis in January by federal officers amid Donald Trump’s immigration crackdown, Fowler wrote that they had been “killed because they and others were violent and/or reckless” (neither victim engaged the officials in violence).

In February he penned a column that accused liberals of condoning violence. He wrote that “liberal logic” dictated that “Christian conservatives must be shut out of public discourse by killing them (Charlie Kirk)”.

In a column from June 2025 he addressed his previous life as a public defender. “I managed a number of death penalty cases in my career. None got the death penalty, although two cases come to mind where it was surely warranted,” he wrote.

In the same article, he recognised that there could be lapses in a criminal justice system in which overzealous prosecutors, “corrupt police”, and “prosecution-oriented judges” can be thrown together. The result can be that “the constitutional protections intended to protect individuals from erroneous convictions are watered down to nothing”.

In the course of last October’s deposition, Fowler related how he came to sign up as Tennessee’s execution doctor. Under the state’s official protocol, he is assigned the responsibility for setting a central line if necessary, and at the end of the procedure he must determine that the prisoner is dead.

Fowler said that he was a friend of the state’s previous death penalty physician. In 2018, “he asked me to accompany him to an execution so that I might take over when he retired.”

That rather bland narrative illuminates little as to motive. Could it be the money? During the deposition it was revealed that Fowler is paid $3,000 for every execution he attends, well below what he might command in other states such as Oklahoma ($15,000) and Arizona ($18,000).

When asked about the payments, Fowler grew tetchy. “I don’t wish to read about myself in the newspaper saying, ‘This bloodthirsty coward doctor gets money for doing this.’ I get paid for the time and effort of going.”

Further insight can be gleaned from an interview he gave NBC News shortly after the failed Carruthers execution. “Every attempt was made to minimize the defendant’s discomfort,” Fowler said. “No one wants Carruthers to suffer.”

But Carruthers’ lawyers say that what they witnessed was alarming. Maria DeLiberato, present in the chamber, was struck that from the moment Fowler entered the room, he took charge.

“Once he came in, it was clear that he was taking over the direction of everything. He was very assertive. ‘Take his socks off,’ he said.”

Fowler began jabbing Carruthers in his left foot, seeking a vein. After about 15 minutes he admitted defeat and refocused his efforts on the much more difficult challenge of securing a central line under the prisoner’s clavicle.

At this point, alarm bells began ringing for DeLiberato and her attorney colleagues. In his deposition, Fowler had said that the last time he had attempted a central line was back in his ER days, about 13 years previously.

The procedure is complicated and fraught with potential mishaps. To be adroit at setting a central line you have to refresh your abilities regularly.

“Nobody should be doing a dangerous procedure such as a central line unless they do it routinely and frequently, so that their skills are maintained,” said John Greer, a retired physician. Greer was among 50 medical experts who wrote a joint letter to Tennessee’s Republican governor, Bill Lee, lamenting the involvement of medical professionals in state executions.

Kit Thomas, the deputy chief of Nashville’s capital habeas unit, was present at the deposition when Fowler revealed the long hiatus in him placing central lines. She was also on hand to give real-time legal advice as the Carruthers execution was proceeding.

When she received a call from DeLiberato saying that Fowler was about to attempt a central line, she went into instant overdrive. “We knew the last time he had set a central line was 13 years ago, so we said, ‘Object! He’s not qualified!’”

DeLiberato did just that. She rushed back into the death chamber, where Fowler was crouched over Carruthers, and objected to the warden that the doctor was unqualified for the job.

“Yes, I am qualified,” Fowler snapped back.

At which point the warden said: “Doctor, do your job.”

Fowler went ahead and cut Carruthers’ skin. DeLiberato is still haunted by what she witnessed next.

“Tony was moaning and groaning in a guttural way that I can still hear. It sounded like agony, and I could see blood slowly seeping out of the puncture.”

Despite the terrible scene, Fowler remained preternaturally calm. DeLiberato said: “He was dispassionate. He didn’t say anything. He didn’t try to reassure anyone.”

The doctor struggled to set up a central line for 16 minutes, as “the patient” groaned “it hurts, it hurts”.

Not able to do what he had been hired to do, he had to concede defeat a second time.

The execution was called off, and Carruthers was sent back to his cell. DeLiberato visited him there about an hour later.

In a declaration she filed for the courts she recalled that the prisoner was “sweaty, pale, tearful, and he seemed to be in shock and pain. He could barely stand or walk.”

Carruthers looked up at DeLiberato and told her Fowler “was hurting me, and knew he was hurting me”.

The Guardian sent Fowler an email and text message detailing how Carruthers had accused him of inflicting suffering. The doctor did not reply.

With days to go to Tennessee’s next scheduled lethal injection, the enigma of the execution doctor is looming large. Carruthers’ sister, Tonya Hervey, has filed a complaint against Fowler with state health authorities alleging he violated medical ethics and caused her brother excruciating pain.

For Kit Thomas, who is a part of the legal team representing Darrell Hines as he prepares to go to his death next Thursday, the revelation of Fowler’s involvement has given us “a peek behind the curtain”. What it showed us, she said, was that the department of corrections was drawing on “unqualified physicians” who were “willing to engage in killing people for $3,000 a pop”.

DeLiberato remains deeply disturbed by what she witnessed, standing just a few feet away as the doctor worked on her client. She believes it should make us all think twice about the asserted humanity of lethal injections.

“They want to make this a medical procedure, but it’s not. It’s premeditated murder. There’s really no way to kill a person humanely, with or without a doctor. What I witnessed was torture.”