The agency filed the chargesheet before a special court in Arunachal Pradesh on Monday naming Luckin Mashangva, Jai Kishan Sharma, Yangte Josaham and Napong Jenpi under charges of criminal conspiracy, murder, attempt to murder of Indian Penal Code (IPC) and Unlawful Activities (Prevention) Act.
The NIA took over the case on June 10 last year from Arunachal Pradesh Police which lodged an FIR on May 21 last year related to the ambush on the convoy of MLA Tirong Aboh near Pansum Thong village in Tirap district by armed cadres of terrorist group of NSCN (IM).
The attack took place while the convoy was moving towards Khonsa from Dibrugarh and a total of 11 persons, including MLA, were killed with injuries to three persons.
"The investigation has established that members of the terrorist group of NSCN(IM) conspired to commit the terrorist act of killing of Tirong Aboh, MLA Khonsa, and 10 others. It was also established that the terrorist act was a result of larger conspiracy due to opposition by Aboh to anti-development and extortion activities of NSCN (IM) in Tirap district," the NIA said in its chargesheet.
The members of NSCN(IM) led by self-styled Major General Absolom of NSCN(IM), who is an absconding in the case, along with other accused formed a terrorist group which was financed by Jai Kishan Sharma to execute the attack, it said.
The NSCN (IM) members had on an earlier occasions threatened Aboh and his supporters for their opposition to criminal activities of the group, said the NIA.
( With inputs from IANS )