Josu Ternera in 2001, when he was a candidate for the Basque party Euskal Herritarrok. EFE

A historic leader of the Basque terrorist group ETA who had been on the run for 17 years has been arrested in France, police sources have told EL PAÍS.

The arrest was made early Thursday morning in Sallanches, in the French Alps, in a joint operation between French and Spanish law enforcement.

José Antonio Urrutikoetxea, 68, better known as “Josu Ternera,” lent his voice to an announcement made in May 2018 confirming that ETA had dismantled all of its remaining structures. The group had ended its decades-long campaign of violence six and a half years earlier, after killing over 800 people.

“French-Spanish cooperation has proven its efficiency once more. The Civil Guard and French Intelligence Service DGSI have my appreciation,” tweeted acting Prime Minister Pedro Sánchez. “Today, more than ever, I send a hug to all the victims of terrorism.”

La cooperación franco española vuelve a demostrar su eficacia. Mi reconocimiento a la @guardiacivil y al Servicio de Inteligencia francés, la #DGSI, por la detención del dirigente de ETA, Josu Ternera, en Francia. Hoy más que nunca un abrazo a todas las víctimas del terrorismo. — Pedro Sánchez (@sanchezcastejon) May 16, 2019

Urrutikoetxea had been a member of ETA for 50 years, holding strategic positions throughout the period and participating in attacks like the one against the Zaragoza Civil Guard barracks in December 1987, which killed 11 people, including five children.

Just a few months earlier, in June 1987, ETA had perpetrated a bomb attack against an Hipercor retail store in Barcelona, killing 21 people and injuring 45. Urrutikoetxea was one of ETA’s top leaders at the time. In May 1991, ETA attacked the Civil Guard barracks in Vic,killing 10 people, five of them minors.

Urrutikoetxea joined ETA in 1968, the year that the group committed its first crime: the assassination of a Civil Guard officer named José Antonio Pardines. Two years later he fled to France for the first time. The death of the leader Txomin Iturbe in 1987 gave him full authority, and the group went on to commit some of its deadliest attacks. But two years later he was arrested in France and sentenced to a 10-year prison term in 1990. He served the first six years in France, then was extradited to Spain.

Urrutikoetxea then entered politics, securing a seat in the Basque parliament in 1998 and 2001. During that time, he represented the radical leftist party Euskal Herritarrok as a member of the parliament’s Human Rights Committee, a fact that was considered a serious offense against the victims of ETA terrorism.

He went missing in 2002, when he received a court summons to make a statement regarding his role in the Zaragoza attack. Despite living in hiding, Urrutikoetxea participated in talks with the Socialist administration of José Luis Rodríguez Zapatero in 2006, when ETA was in the middle of an internal power struggle that was ultimately won by the hardliners Francisco Javier López Peña, better known as “Thierry,” and Miguel Garikoitz Aspiazu Rubina, aka “Txeroki.” Urrutikoetxea was pushed away from the leadership, but regained prominence when the group first announced its plans for dissolution in 2011.

A Spanish court wants to try Urrutikoetxea for crimes against humanity, a legal concept that was introduced in the country’s penal code in October 2004. Three other ETA members were charged with this crime in 2015, but have not been tried as they are serving prison sentences in France.