Mohammad Altaf Ganie alias 'Cheema' was arrested by a joint search party of police, Rashtriya Rifles and CRPF in his Raipora village of Pattan, 30 kms from here, a police spokesman said.
Terming the arrest of Ganie as a "breakthrough", the spokesman said that he was involved in the killing of Sarpanch Ghulam Mohammad Yatoo in the village in September.
However, his other accomplice in the killing - Shabir Ahmed Sheikh alias 'Shaka' - is still at large and efforts are on to nab him, the spokesman said.
Arms and ammunition including AK-47 rifle, four magazines, and 192 rounds of ammunition were recovered from the possession of the militant, he added.