Piyasiri joined the JVP through Ragama Some after listening to a speech by
Upatissa Gamanayake at a JVP rally in Veyangoda in 1978. He participated in the education camp held at Pallewela Muddaragama in the Mirigama electorate which was conducted by Wickramarala Jayatilleke. Piyasiri is the second best student in the history of the university with the highest number of marks. After graduating as a Commerce graduate, Piyasiri opted for full-time JVP politics instead of a job. He later became a JVP organizer for the Kolonnawa and Ratnapura electorates. His commitment to rebuilding the JVP was appreciated and in October 1985 he was appointed to the JVP Politburo. The first formal discussion on the formation of the
Deshapremi Janatha Viyaparaya (Patriotic People's Movement), the armed wing of the JVP, was held for two days on March 4 and 5, 1986 at the Ratnapura canal and Piyasiri was appointed as the leader of the military wing at the Politburo meeting held there. The strategy was for the security forces to retreat without fighting in powerful situations and to launch vigilante attacks when they were weak. • Katunayake Air-force base (April 1988). •
Magazine prison break (December 1988). • Pannala Army detachment (1989). • Panagoda Army base (1989). After Wijeweera's assassination, Piyasiri became the leader of the JVP on November 28, 1989, at a meeting of the Political Bureau held at Panukerapitiya, Ratnapura. Later the government issued a statement on November 28, 1989, stating that they wanted to arrest
Somawansa Amarasinghe, Shantha Bandara, Saman Piyasiri Fernando, Gamini Gunasekara and Upali Jayaweera and that valuable rewards would be given to those who provided information about them. On December 27, 1989, a special police team, led by SSP Lionel Gunathilake, arrested Saman Piyasiri, along with his mother and fiancé, who is a sister of JVP politburo member Daya Wanniarachchi, at Koswatte, Nawala, at a rented house owned by Mark Antony Fernando, who works at
SLBC. According to the police sources, the number of military books found inside the house and some of them are not found in Sri Lankan military libraries. Piyasiri was arrested on December 27, 1989, while staying at a house in Koswatta, Nawala by the special police team. As the second leader of the JVP on November 28, 1989, Piyasiri was the leader of the JVP for 32 days until he was assassinated on December 29, 1989.
Rohan Gunaratna also stated that before Piyasiri's death, he managed to deliver a speech to the interrogation personnel around him about the society of Sri Lanka based on
capitalism and
socialism. Rohan further stated, "but Saman Piyasiri has not given any single information which could harm the party during the interrogation". The killings of rebels, their families, relatives and friends also intensified with these attacks. Due to Piyasiri's inability to stay on target, the entire JVP machinery was destroyed by the security forces within seven weeks. Within seven weeks of Wijeweera's assassination, 12 of the 13 members of the First Politburo were assassinated and only Somawansa Amarasinghe was left. Meanwhile, nine of the 11 members of the Second Politburo headed by Piyasiri were also killed. Only Somawansa and Gamini Gunasekera were left. ==In popular media==