Cecil Clayton was executed Tuesday by the state of Missouri. At 74 years old, Clayton was the state’s oldest death row inmate. He landed on death row after he murdered a police officer, Christopher Castetter, who was dispatched to a house where Clayton had broken in, back in 1996. This is not Serial—there was no question that Clayton committed the crime. The controversy arose over something that occurred two decades earlier.

In 1972, Clayton suffered a devastating injury when the sharp end of a log he was working on in a Missouri sawmill broke off and penetrated his skull. To save his life, neurosurgeons opted to cut away 20 percent of Clayton’s frontal lobe, nearly one-eighth of his entire brain. This is often done to accommodate a rapidly swelling brain that could potentially induce brain death if not emergently corrected. Clayton walked away from the operating room, but there is little doubt he was a changed man. To understand more clearly why losing this part of the brain could drastically change someone’s personality, we must turn to one of the most famous individuals in neuroscience.

Phineas Gage is not a neuroscientist, neurosurgeon, or brain expert of any kind, however. Rather, Gage is a patient known to nearly every disciple of neuroscience. His story begins, well, a very long time ago. An explosion at the railroad where Gage was employed drove an iron rod straight through Gage’s skull, destroying much of his left frontal lobe. Gage’s injury was not fatal, but like Clayton, he became a changed man. He transformed from quiet to brash, from docile to impulsive—his friends remarked he was “no longer Gage.” The man was no longer recognizable.There are not many folk tales in neuroscience, but the tale of Phineas Gage persists. It set the stage for neuroscientists to understand the function of specific region of the brain termed the “prefrontal cortex.”

We now understand that the prefrontal cortex is critical for problem solving, learning from mistakes, and decision-making. When it is damaged, as in Gage and Clayton, impulses are harder to quell and logical reasoning becomes supremely difficult.

There are a number of syndromes that relate to the function of the frontal lobe. They may all bear different names such as “frontal lobe syndrome,” ‘frontal disinhibition syndrome,” or “frontal release disorder” and can be caused by trauma, as with Clayton, or by stroke, brain tumor, or even an infection.

Clayton experienced transformations eerily reminiscent of Gage’s. Clayton’s brother later testified that after the accident, Clayton “broke up with his wife, began drinking alcohol and became impatient, unable to work and more prone to violent outbursts.” His reading and writing skills dropped to elementary-school levels and he received medical diagnoses ranging from uncontrolled rage to hallucinations and depression.

This is not obscure neuroscientific knowledge; rather, it is well-defined. Three different medical doctors declared Clayton incompetent after he was sentenced to death. This is problematic, as the U.S. Supreme Court ruled in 2002 (Atkins v Virginia) that it was unconstitutional to execute an intellectually disabled individual by the Eighth Amendment, prohibition of cruel and unusual punishment. The definition of intellectually disabled was ironed out last year in Hall v Florida, where IQ score (usually 70, Clayton’s IQ was reportedly 71) alone was not the sole criterion for disability but several indicators of intellectual disability were required to arrive at such a conclusion.

The Missouri Supreme Court rejected, with a sharply divided 4-3 decision, Clayton’s last-minute appeal on the grounds that he was aware of the reason he was sentenced to die. The dissenting justices wrote “The majority's decision to proceed with the execution at this time and in these circumstances violates the Eighth Amendment ban on cruel and unusual punishment.”

Neither the U.S. Supreme Court nor Missouri Governor Jay Nixon intervened and Clayton was executed on Tuesday afternoon. Before Clayton’s execution, the national standard, based on multiple U.S. Supreme Court decisions, on execution of mentally disabled individuals was clear. The Missouri Supreme Court’s decision, and the inaction of the nation’s highest court, have generated a lingering uncertainty about the plight of genuinely sick prisoners.

There is no doubt what Clayton did was wrong and worthy of punishment on all accounts, the question still remains—did we execute a sick patient? Did we fail to advocate for Clayton at multiple junctures where his diagnosis may have been made clearer? This does not have bearing on whether he should have been set free or not; in my opinion, he was clearly dangerous and willing to kill. But could we have learned from him, to help doctors and families prevent the killing of another person some day in the future? I’m not a lawyer, and do not claim to understand the legal system, but as someone who has journeyed with patients and their families through these types of injuries many times, I hope that we as citizens did the right thing for Clayton.