A Spanish man convicted for the 1977 killing of five leftist lawyers in a Madrid trade union office has been taken into custody in Brazil’s biggest city.

The head of the federal police in São Paulo, Disney Rosseti, said Carlos García Juliá was arrested Thursday as he was walking down a street in a middle-class neighborhood.

Rosseti said Spain is expected to request the extradition of García Juliá, who is being held in a cell in São Paulo. The request must be made within the next 90 days.

García Juliá was among those convicted of the 24 January 1977 attack by gunmen linked to far-right organizations against a legal office working for labor unions near the Atocha train station in central Madrid.

Five lawyers were killed as a result of the shots and four more were seriously injured.

It was one of the bloodiest attacks by shadowy neo-fascist groups during Spain’s largely peaceful transition to democracy following the death of dictator Francisco Franco in 1975 after nearly three decades of authoritarian rule.

Rosseti said the 63-year-old García Juliá told police he had been working as an Uber driver and had been living in Brazil since at least 2001, when he entered the country with Venezuelan papers that identified him as Genaro Antonio Flores Mategran.

Police began to investigate García Juliá in May, when they noticed the man had not renewed his 2009 temporary residency visa that had expired in 2011, Rosseti said.

Spanish police officer Jorge Garrigos Juarez, who attended the news conference, said that García Juliá was sentenced to a 193-year jail term in 1980, but in 1991, a judge gave him temporary parole and allowed him to travel to Paraguay where he purportedly had a job offer.

He disappeared after the decision to release him was revoked shortly afterward and Spain requested his immediate return so that he could serve out the remainder of his prison term.

He said García Juliá is believed to have lived in Argentina, Venezuela and Bolivia before arriving in Brazil.