The 40-year-old Bryian R Marak (Millam) hailing from Tura in West Garo Hills district surrendered before district Deputy Commissioner, Shella N Marak and Superintendent of Police, Abraham T Sangma, they said.
Millam had joined the outfit in 2011 and had been holding the post of 'foreign secretary' in the outfit, Sangma said.
Millam used to handle the outfit's relations with other outfits based in Bangladesh and was responsible for communication with other outfits regarding logistics as well materials, the SP said.