Counter-insurgent and Awami League leader Kuka Parray had a bulletproof car but was not using it the day he was gunned down by militants.
Jammu and Kashmir police suspect that someone known to Parray may have tipped off militants about his movements and also that he would not be using the bulletproof car.
Jammu and Kashmir Director General of Police Gopal Sharma said close associates are now being questioned to ascertain whether there was any leakage of information.
Sharma also said that Parray had overlooked security precautions.
"Since he was not going out of his native place Hajan (in Baramulla district), he probably did not feel the need to use his bulletproof car," Sharma told rediff.com from his office in Srinagar.
"We had given him adequate protection. We had posted 25 CRPF personnel at his residence and also provided him protection when he was on the move. We are looking into the incident and effort is to hunt the killers," Sharma said.
Union Minister of State for Home I D Swami said after the killing of another counter insurgent Javed Shah, on August 27, security forces should have been more careful.
"Kuka Parray was a top counter-insurgent and his killing is definitely a setback. It is an unfortunate incident, which should not have happened. He has been gunned down to avenge the killing of (Jaish militant) Ghazi Baba August 30 in Srinagar.
"But we would not allow this to slow down our campaign against terrorism. In fact, we will redouble our efforts and try to kill or nab the culprits," Swami told rediff.com.