Khumlo Abi Anal, 40, the self-styled 'Regional Commander' of NSCN-K, is alleged to be a part of the conspiracy that was hatched to carry out the attack on army men at Chandel area of Manipur on June four, the NIA said.
The accused has been produced before special judge of the NIA who remanded him to the agency's custody till July seven.
This is the first breakthrough achieved by NIA which was handed over the probe in the case within a couple of days of the attack. The investigating agency had deputed a team of experts, led by a deputy inspector general, to the spot.
About Anal, the officials said that after the attack, he got himself arrested in a different case to evade his role in the June four killings.
However, during investigation, his role started surfacing after which he was he was subjected to sustained questioning by NIA sleuths. He finally broke down and has reportedly admitted to being part of the conspiracy, they said.
Giving details about the investigations, NIA officials said that 23 NSCN-K members participated in the attack, including the two killed who were killed in the incident. Out of the remaining 21, NIA has been able to identify 14 NSCN-K cadre members who had carried out the ambush.
The militants had come in three groups and carried out the attack, they said.
During the investigations, NIA examined several surrendered militants of NSCN-K who also helped them identify many of the accused in the case.
In a retaliatory attack claimed to be surgical strikes, Indian army commandos had hit two camps of insurgents at two locations along Nagaland and Manipur borders with Myanmar, inflicting serious damage on insurgents.
After the June 4 attack, Army had carried out surgical strikes on NSCN-K camps located along the Indo-Myanmar border.
It was noticed that insurgents would sneak in from across the border to carry out their strikes and then return there, they said.
NSCN-K, which reneged from a ceasefire in March, has been involved in a series of attacks in tandem with some other militant groups under the banner of 'United Liberation Front of South East Asia'.
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