New Delhi, Oct 7 (IANS): The National Investigation Agency (NIA) has arrested a senior militant of National Socialist Council of Nagaland -- Iask-Muivah (NSCN-IM) for murder of Arunachal Pradesh legislator Tirong Aboh and 10 others, the agency officials said on Monday.

The accused identified as Ellie Ketok was arrested from Dimapur in Nagaland in a joint operation with local Military Intelligence (MI) unit.

It was found that Ketok is a self-styled Sergeant Major of banned NSCN-IM and area commander of Tirap area. He was part of killing team and had fired upon Tirong Aboh and others on May 21, 2019.

The NIA started probe into the matter in June after state government transferred the case to the central investigative agency. In this case, five accused -- Sethok Kangnong, Napong Jenpi, Jai Kishan Sharma, Luckin Mashangva and Yangte Josaham -- were arrested earlier.

The sitting National People's Party leader Tirong Aboh, who was seeking a re-election from the West Khonsa Assembly seat, was killed when he was on his way to his constituency. At around 11.30 a.m., the militants opened fire at his vehicle near Bogapani village in Tirap district.

Aboh was travelling with four civilians and two police personnel.