By this time Checa was working for the Soviet secret service , the NKVD . As secretary of the organization , he was also responsible for the secret or illegal party apparatus , consisting of " special teams " that , for example , had already taken part in murdering Falangists . For this reason several authors have blamed him for having ordered the Paracuellos massacres . Angel Viñas states that the mass killings were ordered or suggested by the NKVD . " His responsibility for both the initial spark and for monitoring and surveillance of the operation is undeniable . " Julius Ruiz does not directly implicate Checa and argues that the killings were mainly managed and promoted by the Spanish , with the Soviets simply giving support . During the war Checa proposed organizing guerrilla groups from the refugees from the areas occupied by the rebels , although until September 1937 he was not allowed to organize these forces as the XIV Corps of the Guerrilla Army . As a Communist leader , Checa was one of the PCE negotiators in talks that ultimately failed over merging the PCE and the PSOE ( '' Partido Socialista Obrero Español '' , Spanish Socialist Workers ' Party )
Paracuellos massacres
Paracuellos massacres
Pedro Checa