Out of the 18 accused, 12 have been arrested so far while six are absconding, the NIA added.(Representative image)

The National Investigation Agency (NIA) on Friday filed a chargesheet in the Ramalingam murder case of Tamil Nadu, naming 18 Popular Front of India (PFI) and Social Democratic Party of India (SDPI) activists for allegedly killing him for interfering in their "religious propagation activity".

The chargesheet was filed before a special National Investigation Agency court in Chennai under relevant provisions of the IPC and the Unlawful Activities (Prevention) Act, a spokesperson for the premier investigating agency said.

Out of the 18 accused, 12 have been arrested so far while six are absconding, the NIA added.

Ramalingam, a native of Tamil Nadu's Thanjavur district, was killed on February 5 by the activists of the Popular Front of India (PFI) and the Social Democratic Party of India (SDPI) "for interfering in their religious propagation activity" at Pakku Vinayagam Thopu village in Thiruvidaimarudur town of Thanjavur, the NIA said in its charge sheet.

Initially, a case was registered at Thiruvidaimarudur police station in Thanjavur. Later, the NIA took over the case.

The accused hatched a criminal conspiracy and attacked Ramalingam, causing his death, with the intention of terrorising people and deterring anyone from further interfering in the religious propagation activity of the PFI and the SDPI, according to the charge sheet.