well... on the occasion of the death of the long-time Chilean communist leader, we (re)learn from RIA Novosti's Vitaliy Arutyunov that "By 1973, Corvalan had already become a senator and was a prominent figure in Chile's political establishment. Communists held all the key posts in Allende's government."
and, RussiaToday reports that
Corvalan... was more known in the USSR as a man who was exchanged for dissident Vladimir Bukovsky.
Vladimir Bukovsky described the Chilean communist as a man “faithful to his ideas and a staunch Stalinist, the type of man very well known in Russia.”
“I did not know him personally, we did not even meet at the moment of the swap,” Bukovsky told RIA Novosti. “I only know his reputation, and everyone knows it,” he said.
“Until his last days, Corvalan wrote articles in his party paper that communism would still return, that now there is a temporary delay, and the future still belongs to communism,” he said.
“It is difficult to say much about him,” Bukovsky noted. From the documents of the central committee of the Soviet Communist Party, it is known that “he was involved in terrorist activities, staging explosions because he asked for explosives, bombs and sent his colleagues to Moscow for special training,” he noted.
The efforts to free Corvalan succeeded in 1976, when the USSR proposed to exchange him for a Soviet dissident and political prisoner Bukovsky, Russianews.ru said. “The US pressed Chile and the swap did take place. Corvalan was granted political asylum, the politician was received [in the USSR] as a statesman.”