[3] Caridad Mercader belonged to a wealthy family from Barcelona of Indiano origin[b] (term applied to a Spaniard who emigrated to the Americas who later returned to Spain enriched) in the early 20th century.

[6] This decision was motivated in part by an episode of forced institutionalization during which she was subjected to electroshock therapy[6] and her former husband's attempts to change her state of "sexual apathy" through visits to local brothels.

At the outbreak of the Spanish Civil War, she participated in the fights against the military uprising in Barcelona and joined the groups that left for Aragon, where she suffered severe injuries during an aerial attack.

In the Soviet Union, Caridad actively participated in conflicts between the different factions of exiled Spanish communists, including with Dolores Ibárruri, La Pasionaria.

Her father, Ramón del Río, was originally from the Spanish province of Santander, but when the family decided to return to Spain, a few years before Cuban independence,[4][21] they settled in Barcelona, where they became part of the city's social elite.

According to the journalist and writer Gregorio Luri—who recounts what was reported by Isaac Don Levine[d] and included testimonies from Enrique Castro Delgado[30] and Pablo Mercader, Caridad's first husband[31]—Caridad began taking painting classes with the Valencian artist Vicente Borrás y Abella [es],[26] in whose studio she was able to establish contact with intellectuals and bohemians.

[6][e][32] At the height of "Pistolerismo" (hired assassins that targeted proletariat groups) in Barcelona, Caridad frequented anarchist circles, even going so far as to provide them with information with which to attack the business interests of the Mercader.

The rest of the Mercader family was left in a precarious economic position,[34] and the Mercader-Del Río couple had to move to a more modest apartment on Ancha Street, in the Gothic Quarter, next to the Basilica of La Merced.

One night in 1923, nurses from the Nueva Belén de Sant Gervasi Asylum, accompanied by Caridad's brothers,[6] entered her house, put a straitjacket on her, and admitted her.

Caridad told her son Luis that it was her anarchist friends who, after finding out where she was, sent her husband and her brothers death threats if they did not let her leave the mental institution, to which they finally agreed.

Levine maintained that Caridad enjoyed telling those closest to her how Maurice Thorez, general secretary of the PCF, Jacques Duclos, and other French communist leaders behaved in bed.

[63] Thus, in its September 1 issue, Treball, the official organ of the PSUC, used Caridad as an example of the women volunteers who had joined the militias due to political commitment and not out of frivolity: "Mercader is far from being the boisterous young woman who dresses in overalls for reasons no one understands like those who appear today in the illustrated pages of certain sensational magazines and even at times in yellow journalism.

[75] Costa-Amic, along with other militants of the anti-Stalinist party, had arrived to Mexico in October 1936, forming part of a delegation that was carrying out a propaganda tour to obtain weapons and money in that country.

[10] Mother and son lived in a palace located on Paseo de la Bonanova, in Sarrià, which had been requisitioned by Ramón,[s] and which had belonged to a relative of the Mercader family.

The palace also served as the headquarters of the general staff of the battalion commanded by Ramón, Jaume Graells, which received training in an old convent—known as the Vorochilov barracks[88] located nearby.

[10] At that time, Caridad Mercader was named head of the Anti-Fascist Women's Group (Agrupación de Mujeres Antifascistas), but she progressively disengaged from mobilization and propaganda tasks as she became more involved in work related to the Soviet political police, which had recruited her at the beginning of that year.

[97] Historians such as Robert Conquest and Hugh Thomas spoke in the same vein, while Sudoplátov, head of the Special Operations department of the NKVD during the Second World War, denied it: "... this would have gone against professional good practice.

[9] León Trotsky, who had been one of Lenin's most faithful collaborators, had lived in exile in Mexico since January 1937, after being forced to leave Norway due to pressure from the Soviet government.

Ramón had been in Mexico for several months, under a false identity and as Sylvia Ageloff's boyfriend, and had dedicated himself solely to collecting information, without having personally met Trotsky.

Despite the persistent requests made by the exiles to enlist and thus defend the Soviet Union, the homeland of socialism, the initial response was negative, both because they were foreigners and because of the future need to use these cadres in their countries of origin.

Caridad spent a few weeks with them at the company's training camp, but, according to the memoirs of Sebastià Piera [es], a PSUC activist, she disappeared before the end of the battle of Moscow.

On the one hand, Caridad supported Jesús Hernández and Enrique Castro Delgado [es], who, after the death of José Díaz, would confront Ibárruri to take control of the PCE.

[ai] Piera described Caridad Mercader like this during her years in the Soviet Union: "...an exceptional woman who felt psuquera [a member of the PSUC, Partit Socialista Unificat de Catalunya] and very linked to Catalonia.

"[140] Based on the information that Enrique Castro Delgado would have provided him in 1960, Julián Gorkin attributed to Caridad Mercader various missions commissioned by the NKVD, such as participation in the failed attack carried out by Soviet espionage against Franz von Papen, ambassador of Nazi Germany in Turkey on February 24, 1942.

[148] Gorkin included in his book on the assassination of Trotsky the confidences that Caridad Mercader would have made to Castro Delgado during the period before her departure from the Soviet Union: "They have deceived us, Enrique.

"[38] According to Castro Delgado, shortly before Caridad left the country, Luis Mercader would have confessed his displeasure at the act: "My mother is going to Cuba, and then she will undoubtedly appear in Mexico, but she sacrifices me by leaving me here.

"[38] On the other hand, Luis denied in his book his condition as a hostage, maintaining that his situation in the Soviet Union was always advantageous, which allowed him to develop his vocation as an engineer, something that satisfied him much more than the tasks to which his mother and brother dedicated themselves.

"[150] As a result, the Soviets ordered Caridad to leave Mexico immediately, and no further attempts were made to free from prison Ramón Mercader, who had to serve his full sentence of 20 years.

[20]: 91 Gorkin made a similar analysis when he first stated that "a dark police apparatus turned Caridad into a terrorist, the mother of a murderer," adding that Ramón was sacrificed to the "blind fanaticism she professed."

According to Goytisolo, it was Martha Frayde, Cuba's representative to UNESCO between 1962 and 1965, who revealed to him the identity of the embassy receptionist, asking him to communicate it to the Cuban Minister of Foreign Affairs Raúl Roa.