Police investigating the terrorist attack in Barcelona have reportedly shifted their focus to a Moroccan imam who they believe radicalized young men and plotted attacks even deadlier than the one that left 13 dead on Thursday. Spanish authorities have identified the suspect as Abdelbaki Es Satty, an imam who previously worked at a mosque in Ripoll, the hometown of several suspects in the Barcelona attack, The Wall Street Journal reports. Josep Lluís Trapero, police chief in Catalonia, said Sunday that Es Satty is “one of our lines of investigation” into the “radicalization” of a group in Ripoll. Both Spanish authorities and officials at the mosque where Es Satty used to work have confirmed that he previously served prison time, though it was not clear for what offense. Authorities have also said he had contact with an individual believed to be tied to terrorism. A spokesperson for the Catalan police said Es Satty may have been killed in a house explosion in the town of Alcanar that has been linked to the terrorist cell accused of carrying out the Barcelona attack.