Colonel Esteban Ventura Novo The Humboldt 7 massacre was the extrajudicial killing of four armed Directorio Revolucionario (DR) members by the Havana police on 20 April 1957.

The four men who were killed while resisting arest had taken part in the Havana Presidential Palace attack and the seizure of the Radio Reloj station at the Radiocentro CMQ Building.

Prior to the incident at Humboldt 7, the Havana police were searching for the four men for their involvement in the attacks on the Presidential Palace and the Radiocentro CMQ Building.

The men were alleged to have been betrayed by Marcos Rodríguez Alfonso (also known as "Marquitos"), a fellow revolutionary who was against the conflict to remove Fulgencio Batista from power.

After an argument with members of the DR, he informed Lieutenant Colonel Esteban Ventura of their location; police promptly converged on the area and shot the men while they attempted to flee.

Marquitos was arrested in 1961 and, after a double trial, he was sentenced by the Supreme Court to death by firing squad on 2 April 1964, and shot two days later.

[4] The attacks on the Presidential Palace and Radio Reloj provoked a strong reprisal by the Havana police as they launched one of the worst waves of repression and violence across the city.

[5] Eleven days after the assault on the Presidential Palace, on 24 March 1957, some of the surviving members of the Directorio Revolucionario Estudiantil met at the home of Andrés Silva on Calle L in el Vedado to discuss and analyze the recent actions of the attacks.

[citation needed] A week later, the DR met in the same place from where the Radio Reloj assailants had departed for the attack on 13 March.

[citation needed] At dawn on 15 April, Machadito looked out the window of an apartment safehouse, observed that a patrol car was guarding the block, and immediately warned the others; however, nothing came of it.

Feeling restless and paranoid, Machadito traveled by bus to make an asylum request with a journalist from El País; this failed, and the group continued moving, sheltering at the Pharmaceutical College on Malecón, where they stayed until the night of 19 April.

Marquitos reportedly betrayed the others over an argument at Humboldt 7, likely over the use of violence, and left the apartment after feeling Westbrook hurt his self-esteem.

Colonel Ventura was known for reportedly being brutal and corrupt, having ordered the killings and torture of many revolutionaries, including several militants that participated in the attack on the Presidential Palace.

After spending time in Costa Rica, Argentina, and Mexico, Marquitos returned to Cuba on 28 January 1959, later traveling to Czechoslovakia on a film scholarship.

At the end of 1962, Marquitos' interrogations were headed by investigator Vicente Gutiérrez, a former Popular Socialist Party (PSP) member.

"[10] Gutiérrez and the other investigators questioned Felipe Mirabal, the former second chief of the Batista Cuban secret police who was imprisoned in La Cabaña, but the resource did not work and he was returned to prison.