Why does the Tamil Nadu government want to release Rajiv Gandhi's assassins, and why does the Indian government oppose it?

Question

The Union Government of India seems to be against the will of the government of the state of Tamil Nadu regarding the release of the convicts in the Rajiv Gandhi assassination case.

For example: The Union Government doesn't want the Governor of Tamil Nadu to grant a pardon to A.G. Perarivalan, one of the convicts. However, the Tamil Nadu government wants to release them.

Which political reasons are behind the Tamil Nadu government's intention to release the convicts, and why is the Union Government opposing this move?

Answer 1

Rajiv Gandhi was assassinated by the LTTE (Liberation Tigers of Tamil Eelam), an organisation which is spearheading the movement to carve a new state for the ethnic Tamils within Sri Lanka. Many politicians, public figures, and the Tamil people within India are sympathetic to this movement whereas the Union Government is not.