Grigulevich was summoned back to Moscow in 1938. In January 1940 he was sent to Mexico, under the code name "Yuzek," to take part in the first attempt on the life of Leon Trotsky, again with Agent Vidali. In the wee hours of May 24, 1940, a group of peasants and miners, led by Grigulevich and David Siqueiros, stormed Trotsky's compound at Coyoacan near Mexico City. In terms of harm, they missed Trotsky and his wife altogether and managed only to wound their young grandson in the foot. (Defector Walter Krivitsky managed to hear of this attempt and sent a warning to Trotsky through Dies Committee member J.B. Matthews. Trotsky acknowledged the warning. In a letter, he responded, "Krivitsky is right. We are the two men the OGPU is sworn to kill.")