Yaroslav Zokhnyuk had emigrated to Spain from his native Ukraine, hoping to earn enough money to give his family back home a better life. He was 48 and had worked as a policeman in his home country. His work had included surveillance of the Chernobyl nuclear power plant. Despite this, his pension was not insufficient to support his family. In Spain he had found work as an employee in an electrical appliance repair shop.
11 March 2004 fell on a Thursday. Early that morning, a number of terrorists with links to Al-Qaeda planted thirteen bombs on four suburban trains covering routes running through Madrid. Ten of the bombs exploded between 7.37 and 7.39 am, when the trains were at Atocha, El Pozo and Santa Eugenia stations and alongside Calle Téllez. 191 people were killed in the attack and around 1,500 were wounded. It was the deadliest terrorist attack in Spanish history. On 3 April 2004, agents from the Special Operations Group (GEO) were about to enter an apartment in Leganés where the perpetrators of the attacks were believed to be hiding when the terrorists detonated twenty kilograms of explosives in an act of collective suicide. The blast killed one of the officers, bringing the total number of people killed by the 11 March killers to 192.