SIVASAGAR, June 13 ? Arpan Saikia alias Niranjan Borthakur alias Keshav Mahanta, ULFA?s commander in-charge of Rongpur Anchalik Parishad was arrested by Dibrugarh district police and Army personnel at Pathalibam under Moran police station yesterday. Army walaid him as he was proceeding to a woman ULFA member?s house, Sivasagar police superientendent K V Sing Dev said today. According to police sources, Arpan Saikia joined ULFA in 1992 and was in Myanmar-based camp for most of the time. He was involved in atleast 20 different cases in Sivasagar. He is being interrogated jointly by Dibrugarh and Sivasagar police in Dibrugarh.