A longtime chief of the Basque militant separatist group ETA was arrested Thursday on the streets of a French Alps town after being on the run for 17 years, Spain’s Interior Ministry said.

Jose Antonio Urruticoetxea Bengoetxea, known by the alias Josu Ternera, has been the most wanted ETA member since 2002. Interpol, the global police body, had issued a red alert against him. Spanish authorities accuse him of crimes against humanity, multiple killings and belonging to a terrorist organization.

ETA, whose initials stand for “Basque Homeland and Freedom” in the Basque language, killed more than 850 people during its decades-long violent campaign to create an independent state in northern Spain and southern France. The militant group gave up its arms in 2017 and disbanded last year.

The Interior Ministry said the arrest took place early Thursday in Sallanches, a town of 16,000 in the French Alps. French intelligence services and Spanish Civil Guard agents took part in the operation. Spanish authorities said Ternera had been living near Saint-Gervais-les-Bains, a winter sports haven close to the borders of France, Switzerland and Italy.

The Paris prosecutor’s office said Ternera was arrested in the street by France’s domestic intelligence service DGSI, based on a 2017 French conviction in absentia for involvement in a terrorist group. That verdict carried a sentence of eight years in prison and barred him from French territory.

Ternera was taken to the police headquarters in Sallanches and asked to see a doctor, and has now been transferred to a hospital, the prosecutor’s office said.

He will be taken to Paris in the coming days to be formally served the arrest warrant. Since he was convicted in absentia, Ternera has the right to request a new trial, the official said.

Spanish Prime Minister Pedro Sanchez said the end of ETA showed that “our commitment against terrorism and for a peaceful coexistence of all people is eternal.”

Spain will ask France to extradite Ternera to stand trial for his alleged crimes, before he completes his prison sentence there, according to Interior Minister Fernando Grande-Marlaska.

The arrest of Josu Ternera has been a maximum priority,” Grande-Marlaska said. “The collaboration and cooperation with French police and courts has been a decisive element in this victory of the rule of law over the ETA terrorist organization.”

Ternera’s voice was identified as one of the two ETA members who read a statement announcing the group’s dismantling on audio recordings released on May 3, 2018, capping decades of the militants’ involvement in underground activities.

Investigators have tracked the 69-year-old’s links to ETA since its violent activities shot it to international prominence in the 1970s. Ternera was one of the negotiators who sat down with Spanish government envoys for talks to try to end the group’s activities in the mid-2000s.

He went on to become a lawmaker in the Basque regional parliament but went into hiding in late 2002 after Spain’s Supreme Court summoned him for his alleged involvement in a bomb attack in the barracks of the Civil Guard in Zaragoza that killed 11 people, including six minors.

In homage to those victims, investigators dubbed the mission to arrest Ternera “Operation Stolen Childhood.”

Spanish courts are seeking him for his alleged part in that massacre, as well as for allegedly being involved in the killing of businessman Luis Maria Hergueta Guinea in 1980.

In response to the arrest, the elected leader of the Basque Country region in northern Spain, Inigo Urkullu, said Basque society had moved past its painful past.

“Basque society is moving toward the future … but with a critical view toward its past and a commitment in the present and future to respect human rights and pluralism,” Urkullu said Thursday.