Researcher Kent Kiehl of the University of New Mexico has spent the past two decades sending a mobile MRI machine to prisons across the United States, scanning the brains of incarcerated people in an effort to identify what he calls the “criminal brain.” His work has become a fixture in American courtrooms, cited in thousands of cases, but critics say the science is unreliable and revives long-debunked eugenic ideas — with grave consequences for defendants.
Kiehl first gained national attention in 2009, when he testified in the sentencing trial of serial killer Brian Dugan, who had raped and murdered a 10-year-old girl. Describing Dugan, Kiehl told a reporter: “He was just utterly and completely psychopathic. A perfect – I mean, I hate to say this word – specimen.” Kiehl’s brain scans and psychopathy checklist scores did not persuade the jury to be lenient; Dugan was sentenced to death, later commuted to life after Illinois imposed a moratorium on capital punishment.
But the case opened the door. From 2005 to 2015, brain-based evidence appeared in more than 2,800 published judicial opinions, according to a 2019 study. The study estimated that neurological arguments for reduced criminal responsibility appeared in roughly 10-12% of U.S. murder trials and about 25% of death-penalty trials. Overall, 40% of serious felony cases referred to brain-based evidence, and the study’s authors said the figures “likely underrepresent” the true prevalence.
Kiehl, 56, has received more than $41 million in funding from the National Institutes of Health since 2005, including over $3 million in grants during the Trump administration between 2025 and 2026. His university webpage says his laboratory at the Mind Research Network in Albuquerque has created “the world’s largest database of brain data” from incarcerated people. After his work with the MacArthur Foundation’s Research Network on Law and Neuroscience, Kiehl said he “lectured to probably every federal judge in America” about evaluating neuroscience.
In 2014, Kiehl and his wife, attorney Lyn Kiehl, began operating a private company called Mindset that conducts brain scans and genetic testing for criminal defendants. According to Kiehl, the company has been involved in more than 200 capital cases.
One of those cases was that of Amos Joseph Wells, a Black man in Texas charged with capital murder after killing his pregnant girlfriend, her mother, and her 10-year-old brother in 2013. Wells’s court-appointed attorneys hired Mindset to coordinate scientific experts. They introduced MRI scans and genetic testing to argue that Wells was biologically predisposed to violence, with one attorney telling jurors: “Amos didn’t ask for his genetics, he didn’t ask for the brain he got.”
The prosecution seized on the defense’s argument. “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.
Wells remains on death row in Texas, with few legal options left. His new attorneys, from the international law firm Cooley LLP, have urged the U.S. Supreme Court to intervene, arguing that the trial was tainted by pseudoscience and racism. The NAACP and 29 scientists and lawyers have filed briefs in support.
“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,” said Matthew Kutcher, a partner at Cooley representing Wells.
Many scientists say the research Kiehl promotes does not justify its courtroom use. Satrajit Ghosh, a neuroscientist at MIT, said predicting human behavior through brain scans is the stuff of “extreme sci-fi.” He compared it to phrenology: “They were measuring bumps and saying, ‘We think this person has this behavior because of these bumps.’”
Dr. Paul S. Appelbaum, a psychiatrist at Columbia University, said the deterministic approach “never works out” because it seeks a single simple explanation for complex, multi-determined behavior.
Sociologist Oliver Rollins, who has studied the resurgence of criminal brain science, said the research raises serious ethical problems because the prison population is shaped by racism. Any brain study conducted in prisons will disproportionately study people of color, Rollins said, and neuroscience has no way to account for that.
Kiehl acknowledged in an interview that the criminal justice system is biased, but he said it is biased toward people of low socioeconomic status, not race. Data shows Black people are more than five times more likely to be incarcerated in Ohio than white people, and racial disparities have amplified since the 1970s.
Responding to criticism, Kiehl said his work is peer-reviewed, publicly funded, and goes through a rigorous ethical review process. In 2018, however, a paper he co-authored in Psychological Medicine claiming an association between psychopathic traits and reduced brain volume was retracted. Kiehl called the errors an honest mistake, blaming a student’s data handling.
Wells’s case, and the broader use of brain-based evidence, continues to divide the legal and scientific communities.