While carrying out social work among rural peasants, she began training to become a guerrilla fighter and decided to join the armed struggle against the Mexican government after the 1973 Chilean coup d'état.

[2] Her grandfather, Jorge Prieto Laurens, had fought in the Mexican Revolution as a Zapatista, but after their defeat, shifted towards reactionary politics and promoted anti-communism.

[1] As a young teenager, she read the works of Leo Tolstoy, as well as the contemporary French philosophers Louis Althusser, Michel Foucault and Jacques Lacan,[4] who she described as "intelligent but confused".

[4] Her sister Ayari remembered that she rescued dogs and wanted to be a zoologist, she loved chocolate and was averse to fire, she was argumentative and kept a diary in which she quoted the writer Hugo Hiriart [es].

According to her uncle Luis Prieto, "her parents gave her great freedom, an education with the possibility of discovering for herself sexuality, the pains and rewards of sentimental life, without guilt."

During this time, she engaged in social work in Tlaxcala and the State of Mexico, training rural peasants in cuniculture and soybean cultivation, teaching classes and helping to construct public infrastructure.

[3] By late January 1974, Prieto and the Benavides sisters were putting themselves through military training, which consisted of classes in political theory as well as ballistics and target practice sessions.

[4] Around this time, another FLN safe house had been discovered by the Mexican Armed Forces, who raided the location and arrested the militants Nora Rivera and Napoleón Glockner.

[10] The Prieto family was unaware that Dení had joined the FLN and were only informed of her death a week later, when the Army reported the operation in Mexican newspapers.

[5] In the subsequent decades, Elisa Benavides was able to piece together and record testimonies of the raid on the safe house for the prosecution of Mario Arturo Acosta Chaparro, who had organised and led the attack.

[11] Together with Julieta Glockner, who was also killed in a clash with the army, and Elisa Irina Sáenz Garza, who has been missing since 1974, Dení Prieto is cited as one of the few women known to fought for the FLN.