Iosif Romualdovich Grigulevich (Russian: Иосиф Ромуальдович Григулевич; May 5, 1913 – June 2, 1988) was a Soviet secret police (NKVD) operative active between 1937 and 1953, when he played a role in assassination plots against Communist and Bolshevik individuals who were not loyal to Joseph Stalin.

[citation needed] In the late 1930s, Grigulevich was sent to Spain to monitor the activities of the Workers' Party of Marxist Unification (POUM, the militia with which George Orwell served), during the course of the civil war in that country.

Grigulevich worked under NKVD general Alexander Orlov, using the code names MAKS and FELIPE, and organized so-called "mobile groups" that killed, among other actual and suspected Trotskyists, POUM leader Andrés Nin.

In the wee hours of May 24, 1940, a group of Stalinist agents, led by Grigulevich and David Siqueiros, stormed Trotsky's compound at Coyoacan near Mexico City.

"[6] After the failed attempt to assassinate Trotsky, Grigulevich and two of his accomplices (Laura Araujo Aguilar and Antonio Pujol Jimenez) were helped by Pablo Neruda to escape from the Mexican police.

[2] In 1949, with the help of Joaquín Gutiérrez, a Costa Rican writer who harboured very pro-Soviet and Communist sympathies and who worked in his country's diplomatic corps, Grigulevich procured a false passport identifying him as Teodoro Castro Bonnefil, and settled in Rome.

[10] Grigulevich pretended to be the illegitimate son of a wealthy Costa Rican coffee producer and styled himself Teodoro B. Castro (using a middle initial in the "American manner").

In his role as the Costa Rican ambassador (he presented his credentials on April 25, 1953[11]), Grigulevich met with Tito on several occasions, but the death of Stalin in March 1953 interrupted the assassination plans.

For fear that his identity would be exposed, Grigulevich was eventually summoned back to Moscow, marking the end of his career as a Soviet secret agent.

In Rome, the sudden disappearance of the Costa Rican ambassador, along with his wife and daughter, created a stir, with rumors of Mafia involvement circulating in diplomatic circles.