Deputy Superintendent of Police Mohammad Ayub Pandith was stripped and stoned to death by a mob of more than 200 outside the historic Jamia Masjid in downtown Srinagar's Nowhatta area on June 22. He was on security duty outside the mosque.
The mob violence had drawn widespread condemnation.
"The investigation is ongoing and hunt for the mastermind is on," said Inspector General of Police Munir Ahmad Khan, adding that belongings of the officer had been recovered from the accused.
Earlier this month, a young Kashmiri man, who played a key role in the lynching was shot dead in an encounter in Budgam district. Police had said Sajad Ahmad Gilkar had joined Hizbul Mujahideen after the lynching incident.
Police said the killing of the officer was a spontaneous act and did not look like a pre-planned one.
Jammu and Kashmir Chief Minister Mehbooba Mufti condemned the incident.
(With inputs from IANS)