Principio y discordancia

Principio y discordancia is the investigative maxim Amaia Salazar articulates when the cases appear to make sense only if their most disturbing detail is treated as an exception. The discordance supplies the clue; the principle supplies the origin. Together, they turn a repeated irregularity into a path toward the person who has been shaping events behind the apparent perpetrators.

The rule: anomaly and origin

Amaia’s formulation is that, in a murder investigation, discordance gives the key and principle gives the origin; within every origin lies the ground of its end. The method begins not by smoothing away an inconsistency, but by asking why it is there and whose actions would explain it. Its force is causal: the detail that resists the first account may disclose the organizing hand behind it, and that hand may also reveal where the chain of crimes is leading.

The phrase takes shape through repeated reversals in Amaia’s reasoning. She first names discordance before principle, then reverses the order, before explaining how the two work together. The shift matters less as a change of doctrine than as a tightening of the inquiry: a mismatch becomes useful when it leads back to an origin rather than remaining an isolated oddity.

A signature that does not belong to the confessed killers

The recurring postmortem removal of an arm is the central discordance in the series of partner killings. The apparent offenders share features of familiar domestic violence cases: a close relationship to the victim, prolonged abuse, substance misuse, and impulsive violence. Yet the same arm is removed after death in each case, and the missing limb is not accounted for by those patterns. In one case, the husband confessed to killing his wife but denied any part in the amputation. His admission explained the death, not the absent arm.

A wall inscription offers another sign of a common hand. A prisoner had scratched the word TARTTALO into plaster with a toothbrush handle; although the wall had been painted over, the grooves remained visible in a photograph. Amaia later points out that the Logroño killer died by suicide in his cell leaving the same message in identical handwriting, with an unusual double-t spelling. Because the amputation details had been withheld from the press, she doubts that the shared methods are simply imitations. The repeated mark and missing arm suggest a single operator working across cases, distinct from the violent men who confessed to the killings.

Similarity is evidence, not proof

Forensic comparison strengthens the connection but also sets limits on what can be claimed. Doctor San Martín finds that the cuts on the recovered adult forearm bones share a technique and appear to have been made by a right-handed person with comparable force and confidence. Their resemblance to the cut on Johana Márquez’s arm is striking, but photographs cannot establish the cutter’s identity, the bones’ exact age, or whether the arms were amputated surgically or taken from graves. Direct casts and the original samples would be needed for a firmer comparison. The maxim therefore does not license certainty from resemblance alone; it directs attention while leaving the evidentiary boundary intact.

Other material connections show how an unexpected match can disclose a hidden origin. Bones initially considered compatible with a mairu-beso were identified as belonging to a newborn, approximately 150 years old; routine DNA testing found a 25 percent familial match with Amaia. Separately, analysis dated an antique scalpel sent from Estella Sanatorium to the seventeenth century, and found that its metal had the same alloy and forging as the metal tooth embedded in Lucía Aguirre’s bone. These results do not all prove the same proposition, but each transforms an apparently isolated object or remnant into a line of inquiry about source and connection.

The origin behind the crime

The principle reaches its clearest application in the question of how the arm was taken from Johana Márquez. Jasón Medina had killed her impulsively and left to fetch a rope, intending to imitate a crime he had read about. When he returned, her arm was gone. Amaia asks how the operator could have arrived at precisely the right moment if Medina had not planned the murder. The answer is that the operator was following him: someone skilled at recognizing and recruiting killers had tracked an unpredictable offender rather than controlling the crime in advance.

Amaia’s final interpretation locates a further discordance in Doctor Berasategui’s own pattern. His fixation on Johana led him to depart from his usual method; the attachment became the exception that exposed him. The case’s hidden origin was not merely a repeated signature but the manipulator who had exploited other people’s violence and, through his own departure from routine, left investigators the clue they needed.