Kent Kiehl loves to talk about the criminal defendant who first put his controversial brain research on the map, the serial killer Brian Dugan.

“He was just utterly and completely psychopathic. A perfect – I mean, I hate to say this word – specimen.”

In 2009, Dugan’s lawyers asked Kiehl to testify about Dugan’s inclination for killing.

At the time, a jury in Chicago was deciding whether to sentence Dugan to death for the rape and murder of a 10-year-old girl. Dugan had already confessed to the murder in 1985, while he was serving a life sentence in state prison for the rape and murder of two other women. DNA evidence later established that Dugan had been at the crime scene.

In the words of one of Dugan’s attorneys, the case was “a slam dunk for the prosecution”. Out of desperation, they summoned Kiehl, a researcher at the University of New Mexico who has made it his specialty to study the brains of the incarcerated, as their star witness.

Dugan was certain to be found guilty. But, were a brain scan to identify him as psychopathic, his attorneys could argue in court that Dugan should not be sentenced to death because he was not emotionally capable of sensing right from wrong.

Kiehl thought he might have the answer Dugan’s defense attorneys wanted. He tested Dugan’s brain the same way he had tested more than 1,000 prisoners before. He interviewed him for hours, then applied his answers to a psychopathy checklist that screened for 20 traits and behaviors, like “grandiose sense of self-worth” and “pathological lying”, and assigned each trait a score. Dugan’s checklist score met the threshold for a psychopath, so Kiehl scanned his brain using what was at the time a new technique, called functional magnetic resonance imaging (fMRI), to search for any brain abnormality that might explain Dugan’s psychopathy.

During fMRI scans, researchers map which brain regions are activated in response to certain images. Kiehl scanned Dugan as he was shown pictures designed to provoke emotional responses, like a man yelling at a child or a surgical procedure.

“His score is in the highest range of any of the inmates I’ve ever met,” Kiehl told the jury, referring to Dugan’s score on the psychopathy checklist. “He’s had these symptoms and problems from a very early age.”

In an autobiographical account of his research, published five years later, Kiehl wrote that the scans showed Dugan’s brain was “atrophied”.

Dugan’s trial, 17 years ago, was one of the first US court cases to admit brain research as evidence. The case made national news. But Kiehl’s evidence didn’t convince jurors to be lenient. They sentenced Dugan to death. His sentence was later commuted to life in prison, only after the state of Illinois imposed a moratorium on the death penalty.

But what happened in the aftermath was seismic. In the years that followed Kiehl’s testimony, the science of biological criminality, though shaky, was invoked in thousands of cases.Defense attorneys, in particular, used biological evidence like brain scans to argue that their clients should receive lighter sentences.

From 2005 to 2015, the use of brain evidence in criminal defenses appeared in more than 2,800 judicial opinions, according to a 2019 study. The researchers estimated that neurological arguments for reduced criminal responsibility appeared in roughly 10-12% of US murder trials, about 25% of death-penalty trials. Overall, 40% of serious felony cases referred to brain-based evidence.

Even those figures don’tfully capture the prevalence of neuroscience-based evidence in criminal cases in the US. The study acknowledges that the 2,800 figure “likely underrepresents” such evidence, since it only captures published judicial opinions that reference brain-based arguments.

The biological argument in many of these cases is roughly similar. Echoing Kiehl’s research, attorneys would argue that some people are just programmed for criminal behavior, through no fault of their own.

Few scientists have pursued that argument more aggressively than Kiehl, who, after Dugan’s trial, became the public face of criminal brain science. He has spent the last two decades sending his mobile MRI machine to prisons and jails across the US, in an attempt to identify people with a “criminal brain”.

Critics argue these claims outrun the science, reviving an old and long-debunked idea: that criminality can be read in the body – a modern echo of eugenic thinking that once influenced US courts and public policy.

In the US, where people of color are disproportionately arrested, tried and convicted at higher rates than white people, evidence that relies solely on biological factors is also ethically dubious.

But beyond the disputed nature of the science, using biological evidence in courts can also be a double-edged sword. While defense attorneys have used it to argue for lighter sentences, it is sometimes used to make the case for more severe punishment by suggesting that some people will for ever be prone to violence.

Despite these misgivings, criminal brain science, a long discredited relic of scientific history, has returned.

The stakes are profound. A body of science that many researchers describe as unreliable has now become routine in capital cases. In US courts, this illusion of scientific certainty has led to some defendants being sentenced to death.

Kiehl likes to talk about the many occasions on which he has sat across from a prisoner and identified them as a psychopath. “They’re so utterly and totally different than the rest of us,” he says, gleefully. “It’s totally shocking … I just love it.”

He boasts about his bravery around those with criminal pasts. Most other psychopathy researchers “are never going to go into a maximum-security prison. They never could, they just wouldn’t,” he said. “It’s because it’s scary.”

Kiehl, 56, speaks in a high nasal pitch and delivers his thoughts in a rapid-fire narrative style.

During three lengthy phone interviews between November 2023 and February 2024, Kiehl described himself as an iconoclastic researcher who hoped that scientists can one day find a cure for criminal violence. He even invited me to his lab to scan my brain and experience his methodology for myself. (A week before I was due to travel to New Mexico, he rescinded the invitation and has since refused my requests for further interviews and the opportunity to comment on this story.)

Kiehl grew up in Tacoma, Washington – about a mile from the home of Ted Bundy, the notorious American serial killer.

Kiehl’s father, a reporter and news editor, covered Bundy’s criminal trial for the local paper. His childhood friends refused to go anywhere near the areas where Bundy had murdered his victims. But being so close to the horror sparked his interest in studying the human capacity for destructive behavior. “Where I grew up, there was this fear. And I just remember that there was just no one who studied them,” Kiehl said of serial killers.

Kiehl’s mother was 16 years old when she had him, he said, and he spent the first two years of his life in an orphanage. A Catholic couple in Tacoma adopted him. He learned of his adoption at around age 12, on a family vacation in Phoenix, when one of his adoptive sisters blurted out the truth during a fight.

The revelation violated his sense of trust. After the fight, Kiehl briefly ran away from his family. “It definitely was a good excuse for some juvenile delinquency.”

But he was academic, and went on to study psychology as an undergraduate at the University of California, Davis, where he decided, by the end of his degree, “the number one thing I’d like to study is psychopaths”.

In the 1990s, if you wanted to study criminals, there was only one place to go, Kiehl said – the laboratory of Robert Hare at the University of British Columbia in Vancouver, Canada. He had pioneered psychological research on prison populations. So, Kiehl courted him.

It took over a year for Hare to accept Kiehl into his lab. To try to win him over, Kiehl said he drove through a snowstorm to Hare’s home and brought him bottles of wine. “He thought I was nuts,” he said. “I just said: ‘I might not be your smartest student, but I will be the hardest-working student you’ve ever had.’”

Hare told me by email that he hesitated in accepting Kiehl because “his first few years at Davis were not impressive”.

Kiehl said he would never forget the day Hare relented. “He just called me and told me that he was going to accept me and that he expected big things out of me.”

Kiehl has remained in academia ever since. In 2007, he accepted a neuropsychology position at the University of New Mexico. His university webpage proclaims that his laboratory, which operates under the Mind Research Network in Albuquerque, has created “the world’s largest database of brain data” from incarcerated people.

Today, Kiehl is one of the few remaining contemporary scientists in America who concentrate their research on the incarcerated. (Criminal neuroscience is an insular field, populated by a small group of researchers whose papers often trace back to Kiehl.) His theories have been used by defense lawyers trying to convince juries that their clients had brains that predisposed them of violence.

One such defense, the 2013 case of Amos Joseph Wells III, shows how this approach can have grave consequences for defendants.

‘He didn’t ask for the brain he got’: the trial of Amos Wells

On 1 July 2013, at aabout 7.30pm, Amos Joseph Wells III walked into a police department outside Fort Worth, Texas, and told officers he wanted to die. “Put me in jail. Kill me,” he said.

A police sergeant noticed that Wells was sweating, with a “dazed, kind of spacey look on him”. “Something heavy was on his conscience,” another police officer noted.

Less than two hours before, Wells had shot his pregnant girlfriend, Chanice Reed; her mother, Annette Reed; and Chanice’s 10-year-old brother, Eddie McCuin.

After the shooting, Wells called the mother of his child, Valricia Brooks, and asked to speak to his young daughter. He told her he loved her and to be a good girl. He told Brooks he was planning on killing himself. “I don’t know why I did it. I don’t know why I killed them,” he told Brooks, crying.

Wells later testified that a hallucination of a man in white pointed him toward the police station. When he confessed to the shooting, a detective informed Wells that Chanice, Annette and Eddie had all died. Video footage captured the detective embracing Wells in the interrogation room.

The state of Texas charged Wells with capital murder. He pleaded not guilty. Two state-appointed lawyers represented him at trial, where they introduced a bold defense.

“Amos didn’t ask for his genetics, he didn’t ask for the brain he got, and he darn sure didn’t ask for the parents he got handed.”

This was the closing statement Wells’s lead attorney presented to Texas jurors in 2016, while they were deciding whether to condemn Wells to death. He argued that his genetic makeup should give the jury “cause to pause” before imposing the ultimate penalty.

They had contacted Kiehl and his colleagues to scan Wells’s brain and conduct genetic testing in an attempt to bolster their argument that Wells was biologically prone to criminal violence.

It was a risky strategy.

Wells’s trial judge didn’t allow the jury to see video footage of his expressions of remorse during his police confession – evidence that his new attorneys, who have fought to get him off death row, say could have helped his case, along with a humanizing history of Wells’s troubled life and struggles with mental illness.

Instead, Wells’s own lead counsel explicitly told the jury that Wells had “no control” over his nature. The judge allowed this disputed science to stand as evidence that Wells would for ever present a future danger to society.

Court documents show that, by using the brain and genetic evidence, Wells’s trial attorneys had hoped to secure a sentence of life in prison. Instead, just as in Dugan’s case, the jury condemned Wells to death.

A decade on, Wells is now represented by attorneys at the international law firm Cooley LLP, who have urged the supreme court to intervene in the case. They argued that Wells’s trial was tainted by pseudoscience and racism, in violation of his constitutional right to effective assistance of counsel. The National Association for the Advancement of Colored People, the civil rights group, filed a brief in support of Wells, as did 29 scientists and lawyers, and representatives from two US law schools.

They believe the biological evidence Wells’s defense attorneys presented at trial, rather than help spare Wells’ life, made a powerful argument for his execution.

But what is it about the evidence presented in this case by Kiehl and his colleagues that these scientists and attorneys find so troubling? And what does it mean for the thousands of other cases that rely on similar evidence?

View image in fullscreen

Picking up where phrenology left off

To understand what went wrong in Wells’s case, it’s helpful to first understand that Kiehl’s hopefulness about discovering the biological roots of criminality, and their potential to remake the criminal legal system, are part of an old and tragic tale.

For more than two centuries, scientists have entered the public arena claiming to have decoded criminality in the human body. Legal practitioners have embraced the science, infatuated by the idea that, under criminal law, human beings may no longer be judged by what they do, but by who they are.

In the early 19th century, the science of biological criminality was called phrenology.

Austrian anatomist Franz Joseph Gall had developed theories of criminal behavior by examining the heads of people convicted of crimes. He ascribed arbitrary terms such as “combativeness” and “destructiveness” to bumps and hollows in their skulls. Through the right types of brain exercise, phrenologists proposed, people could change their brains and characters.

In the US, judges used phrenology to assess the mental states of people on trial for murder, lawyers introduced it at criminal trials to argue for lighter sentencing and police departments used it to determine who might commit future crimes.

Yet by the late 1800s, phrenology had been discredited and was banned from many parts of the US.

A young Italian doctor, Cesare Lombroso, picked up where phrenology left off. While working at an Italian asylum through the late 1800s, he opened the skulls of people incarcerated there and claimed to find evidence of abnormal brains in those who had been convicted of crimes. He wrote the criminal brain resembled that of “the rodent or lemur, or the brain of a human fetus of three or four months”.

By the mid-20th century, biological theories of criminal behavior had fallen out of favor again, carrying the memory of Nazi Germany, where ideas of innate criminality were used as a tool of social control and as rationalization for the murder of millions. In the US, biological theories of crime spurred mandatory sterilization policies and restrictive immigration laws.

Now, Kiehl argues, the science has progressed. It is rigorous and grounded in hard data.

“We wanted to bring the very best science to the legal system,” Kiehl said, referring to himself and his colleagues.

But critics have argued that the ghost of Lombroso lives on in contemporary criminal brain research like Kiehl’s, carrying forward the idea of a deterministic relationship between violent behavior and “abnormal” brains.

“The problem with these kinds of deterministic approaches is that people are looking for a single, simple explanation of a complex, multi-determined behavior. And in the end, that never works out,” said Dr Paul S Appelbaum, a psychiatrist at Columbia University who has studied the use of brain research in criminal sentencing.

Sociologist Oliver Rollins, who has studied Kiehl’s research alongside the resurgence of criminal brain science, said that scanning the brains of prisoners to predict violent behavior raises serious ethical problems, because the prison population itself is shaped by racism.

Black and Latino people are disproportionately incarcerated in the US – the result of decades of unequal treatment by police, courts and other institutions that have consistently produced harsher outcomes for people of color. Any brain study conducted in prisons will therefore disproportionately study people of color, not because they are more prone to violence, but because the criminal legal system has put them there. Yet neuroscience has no way to account for that. That, Rollins said, is an unresolvable contradiction.

On at least one occasion, Kiehl’s research explicitly addressed ethnicity. A 2024 study, using a psychopathy checklist and IQ scores to test an incarcerated group of predominantly Latino boys, said those tools reliably predicted that they would go on to be arrested for felonies.

“So many of these researchers don’t want to go on the record to talk about ethical issues because they feel that they’re going to be painted as either racist or sexist or deterministic,” Rollins, who signed on to an amicus brief in opposition to Wells’s death sentence, said. “But if you’re not going to engage in these kinds of ethical questions, then how do we make sense of the ethics of this particular type of work?”

In response to his critics, Kiehl said that his work is peer-reviewed and publicly funded by the National Institutes of Health. He said his work goes through a rigorous ethical review process. According to NIH data, Kiehl has received more than $41m dollars from the agency since 2005 – including over $3m in grants under the Trump administration, between 2025 and 2026.

Brain imaging is not the only scientific tool used to evaluate who may be predisposed to crime. Analyzing genetic information has also become more common. Since the 1990s, funders like the NIH have increasingly funneled money to studies that examine genetic information as a tool to potentially solve social problems, like crime. But since Donald Trump returned to the White House, such ideas have been more explicitly endorsed.

At a 2020 campaign rally, Trump praised the “good genes” of Minnesota residents, a majority-white state. In a 2024 radio interview, he suggested that immigrants commit crimes because “it’s in their genes.”

The president’s pseudoscientific suggestion that immigrants, or people of particular racial groups, hold particular genes, or genetic predispositions, fits a historical pattern of political rhetoric. When governments want to control a population, science has often been recruited to make the case that the population in question is biologically fated to drive poor social outcomes, like crime.

Kiehl, for his part, accepts that the criminal justice system is biased, but said that he believes it is biased toward people of low socioeconomic status, not race.

“Because if you go to rural Ohio, it’s all Caucasians who are low [socioeconomic status] that are there, but if you go to a city where there’s low [socioeconomic status] dominated by other minorities, then you’re going to get that in the [prison] system, and it is just so biased in that way,” he said.

In fact, data shows that Black people are more than five times more likely to be incarcerated in Ohio than white people. For almost a century, people of color have been disproportionately incarcerated in the US when compared with white people, and racial disparities have amplified since incarceration rates began rising in the 1970s.

Kiehl also told me there could be “a lot of benefit” to scanning the brains of everyone incarcerated in Chicago’s Cook county jail – America’s largest jail system – to see who is most predisposed to violence, which would inform “who should get out and who should stay”. But he acknowledged that local officials would face opposition from people who he had identified as “high risk” for committing new crimes.

“You also have to face the issue of Cook county being 70% African American,” Kiehl said. “People are going to be unhappy that you’re scanning African Americans and saying that there’s something wrong with their brains. And so you have to be able to deal with that.”

In reality, Kiehl “dealt with that” by focusing largely on the brains of prisoners, rather than on the social forces that shape who is policed and incarcerated in US society. Yet his research has attracted tens of millions of dollars in both public and private funding.

A ‘vast over-claimer’ who was ‘leading the marketing’

Kiehl’s promise to uncover the biological roots of criminality gave him a huge public platform. He became one of the most visible public advocates for the use of brain science in the courtroom.

In 2013, he appeared in a PBS docuseries called Brains on Trial, hosted by the actor Alan Alda. In 2014, he published an autobiographical account of his research titled The Psychopath Whisperer, in which he evangelizes about the promise his research techniques hold for detecting criminality. In 2015, he filmed a National Geographic documentary with Morgan Freeman on the nature of evil, where Kiehl and the Shawshank Redemption star interview Dugan side by side in a maximum-security prison.

Yet it seemed to me that, the more questions I asked Kiehl, the more evasive he became. Previous coverage of his work, including a 2008 feature in the New Yorker, had been largely admiring, and he seemed unprepared for scrutiny. Ahead of a planned visit to his lab, he told me that embedding a journalist in his research would be an “extra burden” on his staff and “a stressor that can be avoided”. Then he stopped replying completely.

Eyal Aharoni, a psychology researcher at Georgia State University who has collaborated with Kiehl on crime-prediction studies, described Kiehl’s statements to the media as a kind of marketing campaign. “You need some people to be sort of leading the marketing of the science so that we get the funding to do the work,” he said.

But leading scientists say the promises he was making in the media did not reflect the research he published.

Much of Kiehl’s celebrity was based on a study he published that was supported by the John D and Catherine T MacArthur Foundation in which Kiehl and his co-authors wrote that the brain activity of people released from prison predicted their subsequent rearrest.

Satrajit Ghosh, a neuroscientist at MIT, says that predicting human behavior through brain scans is the stuff of “extreme sci-fi”. It is not currently scientifically possible to have a brain-based view of criminal behavior. “We just don’t have the tools and technologies to measure enough things about the brain to have such strong predictions of any behavior, let alone criminal behavior,” he said.

The brain is still such a mystery, and imaging tools remain so limited, that imaging studies carry the risk of simply confirming what the researchers were looking for, Ghosh said. Using an MRI, a researcher could rationalize any observation they want to see.

“That’s what phrenology is, right? They were measuring bumps and saying, ‘We think this person has this behavior because of these bumps,’” he said. Ghosh emphasizes that many neuroscientists are doing valuable work in this field, but notes a similar reverse inference problem exists in MRI scanning. Some scientists can see brain images materialize on a screen, and then “try to come up with an explanation for it”.

Stephen J Morse, a legal scholar at the University of Pennsylvania who has written about the limited relevance of neuroscience for criminal law, and who once worked with Kiehl, described him as a “vast brain overclaimer”.

Throughout our conversations, Kiehl insisted that his brain scans are a promising method for detecting who is prone to criminality in society. But he understands the idea would be met with reservations.

“If the algorithm says, ‘I’m sorry, you’re going to have to wear an ankle bracelet for the rest of your life,’ or ‘You’re so high risk we are never going to let you out,’” people will push back against the outcome, Kiehl said.

Despite his faith in his technology, even Kiehl has been forced to admit that, sometimes, his research has failed to reflect the certitude of its conclusions.

In an October 2018 paper published in the Cambridge University journal Psychological Medicine, Kiehl and colleagues said that their MRI scans, conducted on 495 prisoners in the Wisconsin and New Mexico prison systems, revealed an association between people with psychopathic traits and reduced brain volume. In February 2019, the paper was retracted with minimal explanation.

When I asked Kiehl about the retraction, he told me in an email that the errors were an honest mistake. He put them down to a student not using the data properly. That student “learned a valuable lesson”, he said.

By that time, his work and influence had already extended well beyond his lab.

From 2007 to 2011, Kiehl served as part of a thinktank of legal scholars and scientists called the Research Network on Law and Neuroscience, which was funded by the MacArthur Foundation until 2021. Its stated goal was to “make neuroscience accessible and beneficial to America’s courtrooms”. As part of this project, lawyers and neuroscientists, including Kiehl, met with federal judges across the country.

Kiehl told me that, while working with the MacArthur project, he had “lectured to probably every federal judge in America” about how to tell good neuroscience from bad.

“I don’t know how many federal judges there are but I did lecture to 1000s of them and I certainly traveled enough over those years to feel like I had lectured to all of the federal judges in the US!” he later wrote in an email. (There are 890 federal judgeships.) He noted that he still lectures to judges. “I talk with many of them routinely and actively consult if they request it,” he wrote.

Critics of the MacArthur Foundation’s judge-education effort, including Rollins, have argued training judges to evaluate neuroscientific evidence may have risked doing the opposite of what it intended. Instead of helping judges apply brain imaging cautiously to cases, it may have given it unintentional legitimacy.

Morse, of the University of Pennsylvania, was part of the MacArthur Foundation’s neurolaw cohort. He said he witnessed many of Kiehl’s lectures to federal judges and found it “frustrating” because Kiehl was constantly overstating the relevance of neuroscientific research for the law. Kiehl did not take in any feedback from Morse or his colleagues, he said. Kiehl just “brushed it off”.

The year after Kiehl’s tenure with the MacArthur Foundation ended, he and his wife, attorney Lyn Kiehl, began operating a private company called Mindset that conducted brain scans and genetic testing for criminal defendants, selling the results to defense attorneys.

Kiehl told me that he had “created” the company, but said his wife, Lyn Kiehl, ran Mindset because conflicts of interest required him to stay behind the scenes. There were “conflicts of interest all over the place,” he said. “So I had to be a backseat driver.” (Lyn Kiehl did not respond to a request for comment.)

Kiehl said that the company had been involved in over 200 capital cases. One of those cases belonged to Amos Wells.

It was in 2014 that Kiehl sent a mobile MRI machine to a jail in Tarrant county, Texas, emails and court exhibits say. There, Amos Wells awaited trial on capital murder charges.

View image in fullscreen

‘Racially charged junk science’: could Amos Wells have avoided death row?

“There are cases that just stay with you,” said Dr Jolie Brams, a psychologist who has worked with defendants in death penalty cases since the early 1990s.

In December 2014, around the same time that Kiehl’s company was helping the defense with its high-risk strategy that Wells’s biology predisposed him to violence, Brams was appointed the mental health expert on Wells’s defense team, where she was tasked with building a comprehensive picture of his life, going back three generations, to “provide a basis for a sentence less than death”, according to American Bar Association guidelines for death penalty defenses.

Her job, she said, was to explain how Wells was influenced by his life experiences. Genetic issues are only “a small piece” of someone’s life story, she said. “We look at larger sociological issues such as poverty and culture. But most of all, we look at the pixels of a child’s life, and we look at their experiences over critical developmental periods.”

Brams noted in her case file that Wells had a history of dissociative experiences that echoed symptoms of psychosis suffered by other members of his family, who had also survived traumatic childhoods marked by sexual abuse, violence and abandonment.

“Environment forms the brain,” Brams continued. Yet Wells’s trial counsel “ridiculed and minimized” Brams’s findings in favor of using evidence that Wells’s genes determined his behavior, she said.

According to court documents filed by new defense attorneys after his trial, Wells was born to an 18-year-old mother in Fort Worth, Texas, in the early 1990s – a city so marked by gun violence that local people called it “Murder Worth”.

“Me and Amos saw all kinds of stuff growing up. It was very violent in our neighborhood,” his younger brother, Amron Wells, testified for Wells’s state habeas petition. “We lived in the hood. I started carrying a gun when I was in the eighth grade because I had to protect myself.”

In their own home, the Wells brothers witnessed frequent bouts of domestic violence between their parents, who were arrested for assaulting each other when Wells was seven years old, court documents say. Wells himself endured severe physical abuse throughout his childhood, including regular beatings with belts and extension cords from multiple caregivers. At age seven, he was sexually abused by one of his caregivers, continuing a tragic legacy in which family members across three generations had become victims of childhood sexual violence.

While in elementary school, Wells suffered from early onset psychosis, documents say. Hallucinations of large beasts and Satan plagued him. His mother suffered from bouts of psychosis as well, and told Wells that his visions were real. He struggled with depression, night terrors and sleepwalking throughout his childhood, and felt abandoned by his father after he disappeared into federal prison without explanation.

Despite Wells’s signs of distress, he never received consistent mental health treatment, his court documents say.

There is no disputing the gravity of Wells’s crimes. But legal scholars and post-conviction attorneys have argued that he was entitled to a competent defense team, and a sentencing determination free from “racially charged junk science” that falsely painted him as remorseless.

Wells, through his attorneys, declined to speak to the Guardian. His family, through his mother, Twyla Franklin, also declined to provide comment. (In a text message, she described Wells as her “sonshine”. Wells’s brother, Amron, wrote by text that Wells, unlike how he has been portrayed in the media, “wasn’t a monster at all”.)

Brams foresaw that it would be dangerous to present a defense centered on Wells’s genes and brain to a jury – especially in the state of Texas.

Texas is one of only two states in the US where, in order to sentence someone to death, jurors must determine whether it is a “probability” that the defendant would be “a continuing threat to society” – a legal standard known as “future dangerousness”.

“Once you start talking about determinism, like genetics, that gets to be very iffy, because people start to wonder, ‘Would that person ever be different?’ And that is probably the worst thing you can do in a capital case,” Brams said.

Brams was part of a mitigation team put together by Wells’s state-appointed trial attorneys, William H Ray and Stephen Gordon, who hired Kiehl’s for-profit company, Mindset, to assemble a team of scientific experts. (Ray and Gordon declined to comment for this story.)

According to court documents filed by Wells’s post-conviction attorneys, Ray and Gordon sought to defend Wells using the same strategy they had employed in the cases of other Black defendants, one focused on “bad” biology. Ray and Gordon also put forward a “violent genetics” theory in their cases, using brain scans, genetic testing and expert testimony coordinated entirely by Mindset.

Although Brams was called to testify, court documents suggest her findings took a back seat to the defense’s focus on Wells’s biology – their evidence from MRI scans, saliva samples and genetic testing all amounted to the same conclusion: that Wells could not control his actions.

The genetic tests were performed by Silvia Pellegrini, a biologist, Kiehl associate and professor of biochemistry at the University of Pisa in Italy, who testified that Wells had a variant of a gene called monoamine oxidase A (MAOA). The defense then called her husband, psychiatrist Dr Pietro Pietrini, another associate of Kiehl’s, to testify that there was a strong connection between the MAOA gene variant and an “increased risk for violent behavior”.

He reassured the judge, Ruben Gonzalez, Jr, that these findings were highly credible.

However, Pietrini’s testimony was “not actually true”, Marcus Feldman, a geneticist at Stanford University who has written about the failures of genetic determinism, told the Guardian.

In fact, by the time of Pietrini’s testimony in November 2016, research linking the MAOA gene to violent behavior had not been reliably replicated, Feldman said. Studies linking individual genes to human behavior had been widely discredited and abandoned by behavioral geneticists.

(Neither Pietrini nor Pellegrini responded to requests for comment.)

Mindset also put forward a psychiatrist named Dr William Bernet who, according to a court transcript, testified that he had initially believed the link between low-activity MAOA and Black people was “marginal”, until he read research by criminologist Kevin Beaver.

Beaver has published studies linking low-activity MAOA in Black people to violence and criminality, and has associated low-activity MAOA with gang membership and weapon use. His work has been celebrated in white supremacist circles, like the neo-Nazi website Stormfront, to justify scientific racism and racial hierarchies.

Bernet ultimately testified that “African-American subjects who have this genetic risk were more likely to get in trouble later through some kind of violent activity.”

Bernet, in an interview with the Guardian, denied ever having testified about Beaver’s research, and said he had never heard of him (ignoring the court transcription, seen by the Guardian, that shows that he did). He said he was unaware of wide scientific consensus on the invalidity of the research, but that his testimony was scientifically defensible.

Following the interview, Bernet sent an email to legal scholar Nita Farahany, a co-author of one of the amicus briefs sent to the supreme court contesting the genetic evidence in Wells’ case, and cc’d the Guardian. “Several statements in your amicus brief are flatly incorrect, and neither Ms. Hopkins nor the Supreme Court of the United States should rely on them,” he wrote. The brief argues that Bernet’s testimony was “constitutionally impermissible” because it “rested on widely discredited genetic studies”.

The prosecution argued that the jury’s task of finding a “probability” that Wells would commit future violence was “easy”, because the defense had “conceded it through all their experts”. They urged the jury to believe the defense’s experts “word for word”.

“One thing they all agreed on is this guy’s dangerous,” the state’s attorney told the jury. “He’s never going to not be dangerous.”

The jury sentenced Wells to death.

He remains on death row.

His new lawyers say that, by introducing expert testimony arguing that Wells was biologically predisposed to violence, his trial counsel conceded the future dangerousness standard to the prosecution.

It is “just inherently risky to present to a jury evidence that your client is inherently dangerous”, said Matthew Kutcher, a partner at Cooley LLP, who is now representing Wells.

“I would say also, just as a matter of common sense, if you tell a jury that a Black man is genetically wired for violence, you’re inviting them to see him through racist stereotypes, not as an individual,” he continued.

According to legal experts and Wells’s post-conviction attorneys, the expert testimony coordinated by Mindset, slid from contested neuroscience and genetics into echoing debunked, racist psuedoscience: specifically that socially bad outcomes, like crime or poverty, are rooted in the genes of certain populations.

Wells has few legal options left and remains on death row.

Since Wells’s trial, Kiehl has continued to collaborate with Pellegrini and Pietrini on criminal brain research. In 2023, they were co-authors on a study alleging they had detected abnormal brain structure in a sample of 800 incarcerated men. The study was republished in May.

Brams, for her part, can’t shake her memories of Wells’s death penalty defense nearly 15 years ago.

“I have never, ever seen a defense focus 90% on a theory that has been unfounded,” Brams said, anger brimming in her voice. “It was upsetting from a professional standpoint, but it was also upsetting from an emotional standpoint, in the sense that I knew intellectually, experience-wise, and in my heart what Amos deserved. And he did not deserve what he got.”