It’s not just one level of analysis but five—five reasons we might expect that poor prefrontalfunctioning could predispose a person to violent behavior. It’s not surprising, therefore, that poorprefrontal functioning is the best-replicated correlate of antisocial and violent behavior.9Fact or artifact? Is there a true relationship between poor prefrontal functioning and homicide, or is itexplained instead by some methodological artifact? We think fact. Group differences in brain functioningcould not be explained away by group differences in age, sex, handedness, history of head injury,medications, or illegal drug use prior to scanning. Furthermore, the murderers could do the task—theirperformance was just as good as the controls’, possibly because the behavioral occipital cortex wasmoreactivated in the murderers than in the controls.10The murderers likely recruited this visual brain area intoaction to help them perform the visual task and to compensate for their poorer prefrontal functioning.Prefrontal dysfunction in murderers is fact, and not artifact.
BUSTAMANTE’S BUST HEAD—AND MONTE’S TESTIMONYOur study constituted the first brain-imaging evidence to show that the brains of a large sample ofmurderers are functionally different from those of the general population. Nevertheless we must becautious. Violence is enormously complex, and prefrontal dysfunction doesn’t apply to all murderers.To illustrate this further, let’s return to Antonio and Randy and delve further into their murderous minds.Antonio Bustamante, as you will recall, was an impulsive criminal who had for years been spiralingdownhill until he finally hit rock bottom in an unplanned, impulsive killing of a defenseless old manduring a botched burglary. As the prosecution attorney Joseph Beard argued, it was a vicious andneedless attack motivated by greed and money. He inevitably sought the death penalty.Bustamante had been charged by the police no fewer than twenty-nine times prior to his arrest forhomicide. His crimes included theft, breaking and entering, drug offenses, strong-arm robbery, andunlawful flight to avoid prosecution. His background and pattern of offending was typical of manylifelong recidivistic criminals. He was your typical thug.With one curious exception. Looking closely at his records, I see that his offending did not start until hewas nearly twenty-two. That’s simply not typical of your recidivistic violent offender, whose antisocialbehavior typically starts much earlier—often in childhood and certainly by early adolescence. And yet byall accounts Bustamante was a well-behaved teenager. So what gives?The defense team, led by Christopher Plourd, looked over his history and the circumstances of thehomicide. Something seemed strange to them too. Bustamante had been very messy and disorganized instealing and cashing the traveler’s checks. There was blood all over them. He’d left his fingerprints