The three accused were arrested from Balipadara area while they were trying to escape, said Inspector General of Police, Southern Range, Amitabh Thakur.
The three accused were identified as Manoj Nahak (24), his brother Narayan (27) and Akhaya Sahu (20) of Bhabarada, while another accused Subash Jena (45) is still at large and efforts are on to nab him, he said.
Angry over the killing of the woman, a mob had gone on rampage and had ransacked the Polasara police station and torched vehicles on August 22 demanding immediate arrest of the accused.
"We have identified the persons involved in police station attack," he said.
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The Police said Kamala Swain and her husband Prakash Swain were chased by the accused persons on Sunday due to a previous grudge. While Prakash escaped, his wife was attacked by the miscreants with iron rod and sword.
She was taken to a hospital at Polasra where she succumbed to her injuries, the police said.
Manoj and his brother Narayan were earlier arrested in March on charges of outraging the modesty of the 20-year-old daughter of the deceased after she lodged a complaint on March 5, they said.
Getting the news of arrest of his father and mother, Manoj and other accused persons allegedly attacked Kamala, the police said.