Deputy commissioner of police Dr G Ramgopal Naik said the victim Sistu Lokanadham's decomposed body, stuffed in a gunny bag, was found near a culvert in Narava area under Gopalpatnam Police Station limits here on June 28.
The arrested accused were identified as the victim's wife Sistu Thulasamma, her brother Chintada Ramanna and her lover Thammineni Subrahmanyam.
According to police, Thulasamma was having affair with Subrahmanyam, her former class-mate and neighbour at her native village.
Lokanadham allegedly physically and mentally harassed Thulasamma, and taking advantage of the unhappy marriage, Subrahmanyam resumed his affair with her.
Police suspected something was amiss as Thulasamma had not registered a missing complaint. During the probe she confessed to the crime.