The main accused in the Meher Bhargava murder case Sachin Pahari was shot at and injured in an encounter with the police in Lucknow, but he managed to escape.
Senior Superindentent of Police Ashutosh Pandey said Pahari was injured in the encounter, but he escaped while two of his associates were arrested.
Police is looking for him in all nursing homes in Lucknow, he said.
The encounter took place in the crowded Kaiserbagh area, he added.
Pandey said one of the two persons arrested were present when Meher (50), wife of Congress leader Luv Bhargava, was shot at by four persons on February 28. She died in a Delhi hospital on March 25.
He said police was also raiding nearby buildings to nab him.
Meher was shot at in the busy Shah Nazaf road area when she protested against passing of some lewd remarks at her daughter-in-law by Pahari and some others outside their Dilip Pur Towers residence.
Pandey said Pahari might have been hit by four to five bullets.
The SSP said the total number of arrested have risen to three in this case.
Police had specific information that Pahari had been hiding in Lucknow for the last couple of days, he said.
He said the encounter was a "close one" and the entire area had been cordoned off as Pahari could be hiding in a house in the area.
Police had taken enough precautions as it was a crowded area and they had to exercise restrain while exchanging fire, Pandey said.
Pahari was a "hardened criminal" and used several aliases and was wanted in connection with several cases of murders and extortion, he added.
Police also raided a flat in Lucknow, which had been alotted to a local journalist where Pahari and his associates were believed to be hiding. He said Pahari used to make telephone calls from this flat.
Pandey said Pahari was familiar with the topography of the area as he used to file tenders for getting contracts for running cycle and motorbike stands near the cinema hall.
The police was under flak from various quarters for sloppy investigation in the case and two sub-inspecors had been suspended on charges of laxity.
The district police was being assisted by the Special Task Force in the investigation, which was being supervised by the Inspector General O P Tripathi.
Uttar Pradesh Chief Minister Mulayam Singh Yadav was monitoring the pace of investigation especially after being criticised by almost the entire opposition including former prime minister Atal Bihari Vajpayee.