Following the incident, the union Awami League (AL) president Ratan Chowdhury was detained outside the centre.
Later in the night he was released and made the prime witness. Assistant presiding officer Harunur Rashid Bhuiyan has also been made witness in the case.
Boalkhali police station officer in charge Abdur Razzaq said the case was filed in the night. They released Ratan Chowdhury after interrogation while Suman is on the run.
The case statement says Nirmalendu Dey fled the Jaisthapura Ramani Mohan High School centre with an EVM on Thursday afternoon while the voting to by-poll of Boalkhali Upazila Parishad was going on.
Later, Ratan Chowdhury collected it from Nirmalendu and brought it back to the centre. At that time, the journalists took his photographs.
Both Ratan and Nirmalendu Dey were working for the AL candidate Rezaul Karim alias Raza Mia in the election.
Rezaul won the election.