The de-escalation of the fighting suggests negotiations are ongoing between the armed forces and rebels
The incident took place in Nijay village.
A police case was lodged following a complaint by the woman's brother, said officer-in-charge Kirpal Kumar of the Rahui police station under which Nijay village falls.
The brother, Sinku Kumar, told police that his sister was married in 2009 to Mahesh Yadav, a police official currently with the Special Task Force.
"My sister objected to the extra-marital affair of her husband with his sister-in-law," he said, adding that his sister was tortured and abused.
Police said six people were named in the complaint, but all of them were absconding.
A manhunt has been launched to arrest them.