"It can be confirmed after receiving the final report of the post-mortem. But initially, it can be said that Biplab was murdered," he added.
Biplab was also a member of the Agriculture and Cooperative Sub-Committee of Awami League.
Biplab, 51, went missing while going to Mohammadpur from Keraniganj to meet his mother on 7 November.
The body of was fished out from the Buriganga river in Jajira area of South Keraniganj on Saturday afternoon, said Shahab Uddin Kabir, additional superintendent of police of Keraniganj circle.
Biplab's family members came to Narayanganj early Sunday and identified body from a photo.
A general diary (GD) was filed at Keraniganj police station in this regard, said deceased's brother Durjoy.