Police in Tangail on Sunday arrested the wife over the killing of former Army sergeant Mohammad Shamim in Gopalpur upazila in 2016.
The detainee, Razia Begum, was the mastermind of the murder, claimed Detective Branch of police.
The arrest was made following the confessional statements of two more suspects -- Sujon, 28, son of Hossain Ali, and Abdur Rahim, 30, son of Abdur Razzak of same upazila who were arrested earlier on Friday.
Officer-in-charge of District DB Ashoke Kumar Singh said Razia Begum planned the murder while her accomplices killed the sergeant as she had an extramarital affair with Sujon.
On August 17, 2016, Shamim went missing after he set out for Dhaka. Police recovered his body with his hands and legs tied from the Boiran River on August 24, reports UNB.
Razia Begum filed a murder case with the local police station in this regard and the case was later shifted to the DB.
