The Idea That Evil Causes Mental Illness

The Idea That Evil Causes Mental Illness is Doctor Sarasola’s controversial account of extreme cruelty: in some people, he argues, evil is not simply an effect of mental disorder but a force that helps bring it about. The theory gives a name to a possibility Amaia Salazar has long feared about Rosario, yet it also leaves her wary of the certainty with which Sarasola joins psychiatry to religious doctrine.

The Doctor’s Distinction

Sarasola presents Rosario’s case as having a particular feature that separates it from other forms of mental disorder: evil. He distinguishes people who commit violence in a moment of rage and later suffer remorse from those who carry out deliberate, horrific acts without that pattern of regret. In his account, ordinary explanations such as drugs or deprivation may help create an opening, but they do not explain what passes through it. The decisive claim is that, for certain people, evil can be the ground in which mental illness takes hold, rather than mental illness being a complete explanation for their cruelty.

His argument is not that Rosario is possessed. When Amaia asks whether an exorcism is being considered, Sarasola dismisses the idea: he considers Rosario evil, not possessed. He says that evil has affected her, but does not believe it has itself driven her mad; instead, he suggests that she became involved with things she should not have, and that such involvement exacts a price. That qualification makes his position more specific than a simple equation of wickedness with madness, even as it preserves his conviction that Rosario’s illness cannot be understood apart from evil.

Theological Framework and Its Limits

Sarasola places his theory within a religious history of inquiry into evil, contrasting the Catholic Church’s centuries of investigation with psychiatry’s limited progress on certain conditions since their earliest medieval documentation. He rejects explanations that make every extreme act a symptom of mental illness or treat a lack of maternal love as a universal cause. In his view, modern psychiatry has blurred the distinction between illness and cruelty, encouraging society to call any atrocity madness and thereby excuse its perpetrator. He invokes the seven deadly sins—pride, greed, envy, wrath, lust, gluttony, and sloth—as a vocabulary for recognizing moral corruption that, he argues, remains present even when people no longer know how to name it.

The doctrine speaks directly to Amaia Salazar’s childhood knowledge of Rosario, but does not settle the question for her. Amaia has understood since she was young that her mother could control her behavior in public while threatening her at night, when no one else could see; the abuse left her with a deeply rooted fear that Sarasola’s words bring painfully close to the surface. She outwardly rejects his claim that evil influences people from outside, proposing instead explanations such as upbringing, deprivation, mental illness, drugs, or company. Yet her disagreement is a deliberate test: she wants to see how far Sarasola’s reasoning goes. His account gives moral language to what she has long sensed, while his confidence and religious certainty still provoke her instinctive distrust.

The Criminal Pattern and Its Anomalies

The novel places Sarasola’s account of evil beside a series of crimes whose visible violence does not tell the whole story. In the cases of Lucía Aguirre and Johana Márquez, each woman was killed by a partner or family member who confessed, while the victim’s forearm had been severed from the elbow after death and the missing limb was never recovered. The investigators distinguish those killings from the repeated mutilation: it is not readily explained by the confessed killers’ motives, and the same arm is taken in each case. A word scratched into a prison wall, TARTTALO, further connects offenders who otherwise appear to have acted alone; the unusual double-t spelling and matching handwriting make it look less like a detail copied from news reports than a recurring signature. The pattern raises a question the medical and moral frameworks cannot answer in isolation: whether the confessed killers account for every act at their crime scenes.

Jasón Medina makes that uncertainty especially sharp. Unlike the other men Amaia examines, he had no known history of violence and did not fit the investigators’ profile of a violent, pressure-building temperament. He confessed to raping and strangling Johana, then sexually assaulting her body, but seemed genuinely unable to explain the amputation. After killing her impulsively, he left to find a rope so that he could imitate a crime he had read about; when he returned, her arm was already gone. Amaia reasons that someone who had no plan could not have arranged for the trophy to be taken at precisely that moment unless another person had been following him. The distinction does not prove Sarasola’s doctrine, but it echoes its central concern: the admitted act and the larger force shaping the event may not be the same thing.

What the Theory Cannot Resolve

The investigation also exposes how easily an account centered on individual pathology can obscure patterns that institutions fail to connect. Amaia explains that the killers confessed, that some denied responsibility for the amputations, and that fragmented records across police jurisdictions kept the cases from being compared; once a confessed killer died by suicide, the file was treated as closed, while relatives’ shame helped keep the violence unspoken. She finds two more women born in the valley who were killed by their partners, one in Bilbao and one in Burgos, identified through death notices placed in funeral homes in the valley, though the available records do not establish whether either woman was mutilated. These discoveries do not confirm Sarasola’s theology. Instead, they sharpen the distinction between explaining a perpetrator’s cruelty and recognizing a wider pattern: a confession may settle who committed a murder without accounting for every act surrounding it, and a psychiatric or moral label cannot substitute for joining the evidence.