Police identified the murdered woman as 21-year-old Aswathy from Adichira.
Main murder suspect Basheer alias Khader Yousuf was arrested today, two days after the body of the woman was found stashed in a sack at a rubber plantation in Athirampuzha area, police said.
According to the police, 35-year-old Basheer from Erattupetta in the district, used to stay in a house opposite Aswathy's residence in Adichira.
Basheer, whose wife works abroad, had allegedly hidden the fact from Aswathy that he was married.
When she became pregnant, he allegedly forced Aswathi to undergo an abortion but she refused following which he murdered her, police said.
An associate of Basheer has been taken into custody for questioning, they added.