She was born to a middle-class family in Sardagna, Trentino, in the north of Italy. Her mother was a pharmacist and her father a prosperous merchant. In 1964 she enrolled in the faculty of Social Science at the University of Trento. She soon became involved with student movements, where she got to know Renato Curcio. Together with him she worked for the publication Lavoro Politico (Political Work). She graduated in 1969. She married in a Catholic ceremony Renato Curcio, after which the couple moved to Milan, where she intended to study for a further two years.
In Milan, the Curcios became full-fledged militants. The Red Brigades were formed with Alberto Franceschini in the second half of 1970 as a result of the merger of Renato Curcio's Proletarian Left and a radical student and worker group. After getting arrested in February 1971 for occupying a vacant house, the Curcios and the most militant members of the Proletarian Left went completely underground and organized the Red Brigades and spent the next three years, from 1972 to 1975, engaging in a series of bombings and kidnappings of prominent figures. Renato Curcio was captured, but freed by Margherita in a raid on the prison five months later, on the 18 February 1975.
In April Cagol, Mario Moretti and Renato Curcio met in a house near Piacenza to discuss their strategy. The movement was growing and they needed further finance to continue the struggle. They decided to follow the example of the South American guerrillas and carry out a series of kidnappings, one of the victims being the industrialist Vallarino Gancia. He was chosen because he was very rich and lived in a region with which they were familiar. According to Renato Curcio, he had also financed a Fascist organization. He was kidnapped on 4 June while on his way to his villa in Canelli, near Asti, bundled into a transporter, and taken to the farmhouse (Cascina Spiotta) on the hills of Acqui Terme. This farmhouse had been purchased some time before by Cagol, and had been used by members of the Red Brigades from Turin. Renato Curcio did not take part in the operation; as a prison escapee, his picture had been published all over Italy, and it was considered too dangerous. Cagol, along with a companion, were left to guard Gancia. Later that evening Cagol phoned Renato to tell him that the operation had been a success. The following morning Carabinieri starting investigating farmhouses in the neighbourhood. Cagol had been on watch during the night, and had gone to bed. Her companion, who took over the watch, fell asleep, and did not wake up until the Carabinieri started knocking at the door. Their escape route was blocked by the Carabinieris' car, so they decided to fight it out. In the ensuing gunfight, two police officers were killed, as was Cagol. Renato Curcio was again captured by the authorities in January 1976, tried, convicted and imprisoned.
- l'Unità newspaper 07-06-1975, p. 5
- Interview with Renato Curcio
- See Giovanni Fasanella and Alberto Franceschini (with an afterword by judge Rosario Priore, who investigated Aldo Moro's death), Che cosa sono le BR ("Brigades Rouges. L'Histoire secrète des Red Brigades racontée par leur fondateur, Alberto Franceschini, together with Giovanni Fasanella." Editions Panama, 2005 review by Le Monde.