The chaos and horror of Spain's second rail tragedy this year has been conveyed vividly by survivors of Wednesday's high-speed crash that has left at least 69 people dead.
But as Spain holds three days of mourning, revelations from leaked audio recordings of the apparent human error in a control room in the minutes before this disaster happened have given way to public disbelief and outrage, in a highly politicised climate, exactly a month before Spaniards go to the polls.
