The militant Liberation Tigers of Tamil Eelam was widely blamed for the assassination, which received condemnation from around the world.

[5] He had been an international observer in several countries, including Pakistan, Chile, Kazakhstan, Ethiopia, South Africa and Nigeria.

[5] On 1 August 1982 T. Thirunavukarasu, the Tamil United Liberation Front (TULF) MP for Vaddukoddai, died and on 14 October 1982 the TULF nominated Kuttimani (Selvarajah Yogachandran), a leading member of the militant Tamil Eelam Liberation Organization (TELO), to be his replacement.

[13] Kuttimani was at that time in prison awaiting trial on charges related to the Neervely bank robbery.

[13] Tiruchelvam and all other TULF MPs boycotted Parliament from the middle of 1983 for a number of reasons: they were under pressure from Sri Lankan Tamil militants not to stay in Parliament beyond their normal six-year term; the Sixth Amendment to the Constitution of Sri Lanka required them to swear an oath unconditionally renouncing support for a separate state; and the Black July riots in which up to 3,000 Tamils were killed by Sinhalese mobs.

[17] Tiruchelvam, along with G. L. Peiris, were the lead authors of President Chandrika Kumaratunga's 1995 constitutional reform and devolution plan (also known as the "GL-Neelan Package" or "The New Deal").

[5][18] The plan involved turning Sri Lanka from a unitary state into a "union of regions", merging of the Northern and Eastern provinces, expanding the subjects devolved to provincial councils, establishment of a mechanism to resolve disputes between the central and provincial governments and greater recognition of Sri Lanka's many minorities.

[22] The plan, which was released on 3 August 1995, was generally welcomed both in Sri Lanka and abroad but was attacked by Sinhalese nationalists and Tamil militants.

[24][26] The LTTE's spokesman Anton Balasingham confirmed to Erik Solheim that they had killed Tiruchelvam, and said it was due to him betraying Tamil interests by supporting the government's watered down devolution package, despite them giving him prior warnings to quit.

[33] On the 25th anniversary of his death, on 29 July 2024, a trailer for a multi-part documentary series on Dr. Neelan Tiruchelvam's life and career was released.