Legal request Castillo formally requested euthanasia in April 2024, invoking the provisions of existing Spanish law. Her procedure was unanimously approved by the Guarantee and Evaluation Commission of
Catalonia in July 2024 and was due to take place the next month. The main obstacle was the opposition of her father, who, with the support of the Christian Lawyers Association (), initiated a series of legal appeals to halt the procedure. All courts rejected the request to stop the procedure and upheld Castillo's
right to die. The father argued that his daughter could not make her own judgements due to her personality disorder, and that the state had a responsibility to protect her. Despite having legal approval, the procedure was delayed for 601 days due to the protracted legal battle. In March 2025, her father's appeal was rejected by a court in
Barcelona that found that Castillo was not incapable of making a decision on euthanasia. An appeal to the
High Court of Justice of Catalonia upheld the euthanasia in September 2025, but permitted an appeal to the
Supreme Court of Spain. On 29 January 2026, the father's appeal was rejected by the Supreme Court, and his appeal to the
Constitutional Court of Spain was dismissed as he did not specify how his human rights were violated. On 10 March 2026, the
European Court of Human Rights (ECtHR) in
Strasbourg, France rejected the father's final appeal. In her final interview, broadcast on
Antena 3's '''' on 25 March 2026, Castillo said that her decision to die was personal and she was not encouraging other people to request euthanasia.
Death On 26 March 2026, Castillo, aged 25, underwent euthanasia at a healthcare centre in
Sant Pere de Ribes in the
Province of Barcelona. Her mother requested to be present in the room, but she chose to die alone. Castillo was the third youngest person to receive euthanasia in Spain. Of the 1,123 people who had received euthanasia, two people, aged 22 and 23, were younger. ==Reactions==