An Imam's family claims he was murdered after his body was found hanging from the roof of a mosque in Osmaninagar upazila.
Police say they are waiting for the post-mortem examination report to determine the cause of death.
Locals and police say Imam Abdur Rahman's hands and feet were tied with rope when his body was found hanging at Sadipur Union's South Mobarakpur mosque on Thursday.
The 45-year-old had joined the mosque in July.
Jatiya Imam Samity's Sylhet unit Secretary Mawlana Ehsan Uddin claimed Rahman had been “murdered in a planned way”.
Rahman's elder brother Join Uddin said he would file a case.
Osmaninagar police station Officer-in-Charge Abdul Awal Chowdhury said the Imam's body had been handed over to his family after post-mortem examination.
An agitation procession was brought out in the city after Friday's Jumm'a prayers protesting against Rahman's death.