By this time he began to show open sympathy for the Communists; Some time later he confessed to the President of the Republic, Manuel Azaña, that he was faithful to the Army, the Communist Party and the Masonic Lodge. After the so-called "May Events", he assumed the post of Chief of Police in Barcelona, a position from which he carried out the repression against the POUM, a Trotskyist-oriented party that had participated in the Barcelona riots together with the anarchists of CNT-FAI. Thus, under Burillo's orders, on June 16 the POUM headquarters at the Hotel Falcón was closed and the party's members, including its top leader —Andrés Nin— were arrested on charges of Francoist espionage. Months later, he ceased in this position, returning to military positions.