Due to his involvement with activities deemed subversive by the dictatorial regime, he was arrested by the military forces and subsequently tortured and murdered.
Paiva's political career began in October 1962, when he was elected Congressman for the state of São Paulo by the Brazilian Labour Party.
Nine months later, he was supposed to fly to Buenos Aires for a meeting with the deposed left-wing leaders João Goulart and Leonel Brizola.
During the lay over in Rio de Janeiro, he left the plane and boarded on a flight to São Paulo, heading to his house, where his wife and children lived.
Paiva then moved with his family to Rio de Janeiro and returned to work as a civil engineer, while continuing to collaborate with and assist exiled left-wing militants and guerrilla members in Brazil and abroad.
Rubens Paiva founded, alongside editor Fernando Gasparian, the newspaper Jornal de Debates and was the last director of Última Hora in São Paulo, before Samuel Wainer sold it to Octávio Frias' Grupo Folha.
Hoping to catch "Adriano" and thus reach Lamarca, the military forces raided Paiva's house in Rio de Janeiro and arrested him on 20 January 1971.
According to documents published by the Brazilian military, the car that was conducting Paiva to the Center for Internal Defense Operations prison was forcibly stopped by unknown individuals that rescued him.
Both reports were written on 27 March 1964, by a Czechoslovak communist political police chief and secret agent operating in Brazil, codenamed Moldán.
The motivation that led Moldán to carry out this work was not due to a specific intelligence task, but an official request made by the Czechoslovak ambassador in the course of his legal diplomatic activities.
[8] He wrote that he was convinced he could use the report to carry out active operations involving Paiva, to exploit his role in the Brazilian parliament.
[10] The screenplay was written by Murilo Hauser and Heitor Lorega, and adapted from the non-fiction memoir book Ainda Estou Aqui by Marcelo Rubens Paiva, Eunice's son.