[1][2] Appalled by the Black July anti-Tamil riots, Jesuthasan joined the militant Liberation Tigers of Tamil Eelam (LTTE) as a "helper" when he was around 15 or 16.

[1][3][4][5] He became a full-time member of the LTTE in 1984, receiving training locally and taking on the noms de guerre "Thasan" and "Buckle".

[3] Jesuthasan's parents fled by boat to Madras, India in 1990 after the Sri Lanka Navy took over Allaipiddy and turned it into a naval base.

[9] In the late 1990s Jesuthasan started writing, under the pseudonym Shobasakthi, short stories, plays, political essays and novels about his personal experiences during the civil war.

[6] Jesuthasan's acting career started in 2011 when he wrote and starred in Sengadal (The Dead Sea), a film about Tamil fishermen struggling to make a living in the largely abandoned village of Dhanushkodi in southern India.

[14][15] The film tells the story of Dheepan (Jesuthasan), a former LTTE member, who claims political asylum in France by finding a woman and girl to pose as his wife and daughter.

[4][19] When Jesuthasan traveled to Canada for the Toronto International Film Festival's screening of Dheepan, he was questioned about his past with the Tamil Tigers.