Case law and legal doctrineCriminal lawInsulin given to a 98-year-old resident: circumstantial evidence, treachery and the reviewable permanent prison term

The facts and the procedural route

• A prior physical assault on a 98-year-old resident with advanced dementia
• Taking of an insulin pen from the treatment trolley
• Administration of several doses to a non-diabetic person, with no medical indication
• Hypoglycaemic coma and death days after admission to hospital
• Jury Court of Leon: twenty years for treacherous murder
• High Court of Justice of Castile and Leon: characterisation upheld
• Supreme Court: reviewable permanent prison term

The legal keys

• Circumstantial evidence: fully established indicia and reasoning consistent with logic
• Absence of a reasonable alternative explanation as the closing element
• Treachery: the conduct removes the victim’s ability to defend herself
• The stealthy nature of the means reinforces the finding, regardless of age
• Article 140(1)(1): particular vulnerability of the victim by age or illness
• Cassation may increase the sentence where the prosecution raises a purely legal question

What circumstantial evidence requires in order to displace the presumption of innocence

The Chamber recalls that a conviction may rest exclusively on circumstantial evidence where two cumulative conditions are met: that the indicia are fully established by direct evidence, and that the reasoning leading from those indicia to the inferred fact accords with the rules of logic and with common experience. A strong suspicion is not enough, nor is an accumulation of equivocal data. What is reviewed on appeal is not the court’s conviction, but the soundness of that chain of inference.

Overall assessment and the alternative explanation

Here the indicia relied on were the defendant’s status as the last person to attend the victim, her access to the insulin pen, the absence of any medical prescription justifying the administration, and a clinical picture consistent with induced hypoglycaemia. The closing element was the absence of a reasonable alternative explanation. That is precisely where most such proceedings are decided: the defence need not prove innocence, but it can introduce a plausible alternative hypothesis that breaks the inference. Where no such hypothesis exists, or where it does not withstand scrutiny, the inference is consolidated.

Treachery and stealthy means

The Chamber locates the essence of treachery in the elimination of the victim’s opportunities to defend herself. A silent and unexpected means, which the victim cannot even perceive as an attack, achieves that suppression with particular intensity. The court stresses that the finding does not depend solely on the victim’s age: the manner of commission would suffice on its own, and cognitive deterioration operates as an additional factor aggravating the wrongfulness.

Particular vulnerability under Article 140(1)(1)

The aggravation leading to the reviewable permanent prison term requires the victim to be particularly vulnerable by reason of age, illness or disability. Ninety-eight years of age combined with advanced dementia amply satisfies that requirement. It should be noted that this circumstance is not to be confused with treachery: treachery describes the manner of execution, whereas vulnerability describes a condition of the victim. Applying both simultaneously does not offend the principle against double punishment, because the grounds differ.