In a new twist to the killing of encounter specialist Rajbir Singh, his wife Narmada has given a clean chit to Vijay Bhardwaj who had confessed to the murder of the ACP and has asked for a CBI probe. ''It is not so easy to kill a top cop. A man cannot do this by himself. He is just a property dealer and would not have the courage to kill him unless he was pressurised. The police needs to investigate this aspect,'' said Narmada Singh, Rajbir's wife.