A youth was found dead inside a septic tank at a local madrasha in Ashashuni upazila of Satkhira on Thursday midnight.
The dead was identified as Jahangir Hossain, 24, son of Khokon Gazi of Razapur village in the upazila. He used to drive motorbike on rental basis.
Police arrested four people - Abdul Aziz, 40, Al Amin, 25, Rabiul Islam, 30, and Shariful Islam, 25 - in this connection.
Biplab Kumar Nath, officer-in-charge of Ashashuni Police Station, said Jahangir remained missing since he left home to go to Eksara Launch Ghat on his motorbike on Wednesday.
Failing to communicate, Jahangir's wife lodged a complaint with the police station, reports UNB.
After investigation, police arrested Rabiul and then recovered the body of Jahangir from the septic tank of Eksara Dakhil Madrasha in the upazila at around 12:00am, according to his statement.
Police also arrested Rabiul's other associates with the help of the local UP chairman.