Jaime Ramón Mercader del Río (; 7 February 1913 – 18 October 1978) was a Spanish <!-- DO NOT CHANGE NATIONALITY TO CATALAN. IF YOU WANT TO CHANGE IT, PLEASE DISCUSS ON THE TALK PAGE FIRST. HIS NATIONALITY IS REFERENCED ON TALK PAGE AND FURTHER CHANGES WITHOUT CONSENSUS WILL BE REVERTED. --> communist and NKVD secret agent who assassinated the revolutionary Leon Trotsky in Mexico City in August 1940 with an ice axe, for which Mercader was imprisoned for 19 years and 8 months.

In 1960, after release from Mexican imprisonment, Mercader was awarded the Hero of the Soviet Union medal and the Order of Lenin medal, and lived at different times in Cuba, the Soviet Union, and Czechoslovakia.

Life

Jaime Ramón Mercader del Río was born on 7 February 1913 in the town of Argentona, in Maresme county, Catalonia, Spain to Eustacia María Caridad del Río Hernández (aka Caridad Mercader), daughter of a Cantabrian merchant who became rich from his business in the Captaincy General of Cuba, and Pablo Mercader Marina, son of a Catalonian textile industrialist. Jaume Ramón was raised in France by his mother Caridad, who also was a communist who fought in the Spanish Civil War, and also served in the Soviet international underground.

In the mid-1930s, young Mercader became a Communist and worked for leftist organizations during the existence of the Second Spanish Republic (1931–1939). He was imprisoned for his political activities, but then was freed when the left-wing coalition of the Popular Front were elected as the government of Spain in 1936. During the civil war, he was recruited by Nahum Eitingon, an officer of the NKVD (People's Commissariat for Internal Affairs, the Soviet secret police), who sent Mercader for secret agent training in the USSR.

Mercader befriended and infiltrated the Trotskyist communist faction during the Spanish Civil War. As a secret agent of the NKVD, Mercader met with the war correspondent David Crook, an English communist and volunteer soldier for the Republican side, in the city of Albacete, Castilla–La Mancha, and there taught him the Spanish language and trained him in the techniques of espionage. Moreover, as a correspondent for the News Chronicle, Crook spied on fellow volunteer George Orwell and other militiamen of the POUM (Workers’ Party of Marxist Unification) and the Independent Labour Party. and the student Ageloff had returned to Brooklyn in September 1939, where Mercader joined her under the assumed Canadian identity of Frank Jacson, facilitated by and with the passport of Tony Babich, a Canadian volunteer soldier in the Spanish Republican Army killed in battle. To assuage her suspicions about his true identity, Mercader told Ageloff that he had bought a false identity in order to avoid military service.

In October 1939, Mercader moved to Mexico City and persuaded Ageloff to join him there. Leon Trotsky was living with his family in Coyoacán, then a village on the southern fringes of Mexico City. He was exiled from the Soviet Union after losing the power struggle against Stalin's rise to power.

thumb|upright=1.15|Trotsky and his wife in Mexico in 1937

Trotsky had been the subject of an armed attack against his house, mounted by allegedly Soviet-recruited locals, including the Marxist–Leninist muralist David Alfaro Siqueiros. The attack was organised and prepared by Pavel Sudoplatov, deputy director of the foreign department of the NKVD. In his memoirs, Sudoplatov claimed that, in March 1939, he had been taken by his chief, Lavrentiy Beria, to see Stalin. Stalin told them that "if Trotsky is finished the threat will be eliminated" and gave the order that "Trotsky should be eliminated within a year."

Through his lover Sylvia Ageloff's access to the Coyoacán house, Mercader, as Jacson, began to meet with Trotsky, posing as a sympathizer to his ideas, befriending his guards, and doing small favors. He made drawings of the villa to help the other groups of assassins. Trotsky's grandson Esteban Volkov, aged 14 at the time of the assassination, emphasized that Jacson had been present in Trotsky's house during the first attack led by Siqueiros.

thumb|upright=1.15|Trotsky's house in Coyoacán, currently the León Trotsky House Museum

On 20 August 1940, Mercader was alone with Trotsky in his study under the pretext of showing the older man a document. Mercader struck Trotsky from behind and mortally wounded him on the head with an ice axe while he was looking at the document.

The blow failed to kill Trotsky, and he got up and grappled with Mercader. Hearing the commotion, Trotsky's guards burst into the room and beat Mercader nearly to death. Trotsky, severely wounded but still conscious, ordered them not to kill the attacker so he could speak.

Caridad and Eitingon were waiting outside the compound in separate cars to provide a getaway, but when Mercader failed to return, they left and fled the country.

Trotsky was taken to a hospital in the city and operated on but died the next day as a result of severe brain injuries.

thumb|right|Official copy (dated 1944) of the sentencing decision passed by the Mexican court on Mercader, listed as "Jacques Mornard Vandendresched or Frank Jackson"

Trotsky's guards turned Mercader over to the Mexican authorities. He refused to acknowledge his true identity. He only identified himself as Jacques Mornard. Mercader claimed to the police that he had wanted to marry Ageloff, but Trotsky forbade the wedding. He alleged that a violent quarrel with Trotsky had led to his decision to murder him.

Mercader stated: