Spain has this week been marking the fifteenth anniversary of the terrorist attack on Madrid's local rail network that killed 192 people, the country's worst ever.
On 11 March 2004, ten bombs in rucksacks exploded on trains during the morning rush hour. At first, in the chaos of the moment, the government blamed ETA Basque terrorists but it was later shown that it was a coordinated plot by al-Qaeda-linked extremists.
For the first time in recent years, the lingering suspicion of some right-wing politicians that there was some kind of conspiracy behind the bombs has resurfaced. The attacks helped turn votes against the conservative PP and usher in the Socialist party in a planned general election a few days later in 2004.
Six acts of remembrance were held at different points in the capital on Tuesday. The prime minister, Pedro Sánchez, led a ceremony outside the regional government's headquarters and was joined by the mayor of Madrid and the president of the Madrid regional government, as well as other political and government leaders.
Later there was controversy at an event at the main Atocha railway station, when the PP's mayoral candidate for Madrid, José Luis Martínez-Almeida, left the gathering early claiming it had been politicised after repeated mentions by speakers that the motive for the attacks had been Spain's involvement in the Iraqui war in 2004. The incoming PSOE government of José Luis Zapatero at the time withdrew Spain from the Iraqui war soon afterwards.
Current leader of the PP, Pablo Casado, said on Tuesday that "the victims deserve to know the truth", in language not heard at the annual commemorations for some years.
However the current Socialist government of Pedro Sánchez was quick to respond to Casado. "A substantial amount of the truth is already known," said Interior minister, Fernando Grande-Marlaska.