When Inés del Río Prada was arrested in Zaragoza on June 2, 1987, she was driving a van filled with 35 kilograms of the explosive ammonal, on her way to the Costa del Sol resort region. Her detention ended one of the bloodiest careers in the history of ETA. The terrorist who took the so-called "Parot doctrine" to the European Court of Human Rights was sentenced to 3,828 years and one day of jail on 23 counts of murder, including the bomb attack against a bus full of civil guards in Madrid in July 1986. Besides the 12 fatalities, another 56 people sustained injuries. The attacks came during the so-called “Years of Lead,” when ETA was at its bloodiest.
Most of Del Río's terrorist attacks were perpetrated in Madrid. Barely a month before the Civil Guard massacre, she had taken part in the assassinations of Major Ricardo Sáenz de Ynestrillas Martínez, Lieutenant Colonel Carlos Vesteiro and their driver, Private Francisco Casillas. Armed with machine guns, the terrorists fired over 50 bullets at the army vehicle as it drove near the Vicente Calderón soccer stadium.
On April 25 of that same year, ETA's Madrid cell killed five other civil guards who were working as bodyguards at the Italian Embassy. This time the killers used a car bomb. Del Río was also found guilty of murdering Rear Admiral Fausto Escrigas outside his own home on Dulcinea street, on July 29, 1985.
In the fall of 1986, following this wave of attacks, Del Río crossed the border into France. She thus avoided being arrested when ETA's safe haven in Madrid, an apartment located on Ulla street, was busted on January 11, 1987.
Inés del Río fled to Algeria following the death of ETA leader Domingo Iturbe, alias "Txomin," who had held failed talks with the Socialist government of Felipe González. Following her return to Spain, Del Río was arrested on June 2, 1987 and sentenced to over 3,800 years after standing trial several times. The 1973 penal code in force at the time established a maximum prison stay of 30 years (it is now 40), but it was possible to reduce this amount significantly through penitentiary benefits involving taking courses and doing workshops. In some cases, prisoners could walk free after less than 20 years. Under this system, Inés del Río was scheduled to be released on July 2, 2008, but a month and a half before that date the High Court applied the Parot doctrine to her and moved her release date to July 27, 2017.