Sylhet municipal workers were seen dumping market waste into the river, a resident says
Police and Rapid Action Battalion personnel initially suspected that the bag carried explosives.
A bomb disposal unit from Dhaka opened it around 9am on Monday and found the limbless body inside.
"The dead man appeared to be between 25 and 30 years of age. The body was found mutilated but we're trying to identify the man,” said Superintendent of Police Shah Abid Hossain.
Mymensingh Range DIG Nibash Chandra Majhi and RAB Commanding Officer Lt Col Iftekhar Uddin and other high officials visited the scene.
"It's a cold-blooded murder. Police are trying to find out the murderers. The body has been sent to the Mymensingh Medical College Hospital morgue for autopsy,” said the SP.