[3][4] Riveros entered the Colegio Militar de la Nación as a first-year cadet on 1 February 1943, after having finished secondary school.

Years later, he trained to be a General Staff Officer at the Escuela Superior de Guerra, which in time afforded him a path into the army's highest levels.

[5][6] Among those who had recently graduated from class 74, of which Riveros was a member, were Sub-lieutenants Albano Eduardo Harguindeguy, Carlos Enrique Laidlaw, Leopoldo Fortunato Galtieri, Otto Carlos Paladino, Ramón Genaro Díaz Bessone and Luciano Benjamín Menéndez, who fulfilled various functions of central relevance during the Dirty War and its de facto governments.

Riveros joined the former, which was in alignment with José Alfredo Martínez de Hoz's economic policies and more inclined to establish dialogues with political sectors.

[13] Once Divisional General Riveros had gone into retirement in January 1980 and no longer bore his military title, Roberto Eduardo Viola's government appointed him Argentina's ambassador to Uruguay on 26 June 1981.

[14] Riveros retained this ambassadorial post under both Leopoldo Fortunato Galtieri's and Reynaldo Benito Antonio Bignone's de facto presidencies, until 10 December 1983, when he was dismissed from his diplomatic functions by the incoming, newly elected constitutional president, Dr. Raúl Ricardo Alfonsín, who named former vice-president Dr. Carlos Humberto Perette as Riveros's replacement.

He was the first military officer to explain his own role during Argentina's state terrorism (the Dirty War), putting together a lengthy document in which he stated, among other things: There have not been any desaparecidos (missing persons), but rather terrorists annihilated within the framework of a revolutionary and therefore irregular war.In Italy, Riveros was sentenced to life imprisonment and 18 months' solitary confinement in 2000 for the disappearance and death of three Italian citizens.

[21][22] On 12 August 2009, Riveros was found guilty in the murder of fifteen-year-old Young Communist militant Floreal Avellaneda, who had been kidnapped on 15 April 1976, and tortured at the Villa Martelli police station and then at Campo de Mayo, together with his mother.