A woman places roses on the vehicle of Catalan regional policemen, known as Mossos d'Esquadra, in Barcelona on August 26, during a march against terrorism which slogan is #NoTincPor (I'm Not Afraid).
Authorities have now raised to 14 the death toll from the van attack on Las Ramblas, in which a terrorist ploughed into pedestrians.
The next day, a ramming and stabbing attack took place in the nearby coastal town of Cambrils, with one person being killed and five others wounded.
The probe into the August 17-18 attacks in Barcelona and Cambrils has suggested that ties of the alleged cell leader to other extremist cells and a criminal record for drug trafficking may have been missed because Catalan regional police didn't have information that was in the hands of central authorities.
Hundreds of thousands of people in Barcelona staged a march in the Catalan city of Barcelona Saturday in defiance of the ISIS-claimed attack last week.
Saturday's massive march in the Catalan capital was led by police officers, firemen and medics, who responded to the attacks on August 17 and 18.
King Felipe VI has joined the public demonstration for the first time for any Spanish monarch.
Europe has been shaken by a spate of deadly Islamist violence with an increasing number of low-tech attacks using vehicles or knives - sometimes both - as weapons. Five assailants in the auto were shot dead by police at the scene. Eight suspects are dead and four more under investigation, two of them in jail. They and Abouyaaqoub were wearing phony suicide belts when they were executed, police said.
Rajoy had appealed to all sides of the political spectrum to take part in the march to show that "Catalonia and the rest of Spain [are] united against terror".
Police, in city capital Barcelona, estimates that almost 500,000 people participated in a march against terrorism on Saturday.
People continued to light candles and lay flowers in Las Ramblas on Sunday in memory of the victims.