A human torso Monday was trawled out of the Sumida River in Arakawa Ward, Tokyo, the Metropolitan Police Department said.
The torso was identified as being that of Toru Narumi, 54, a native of Hokkaido with no fixed address, police said. Narumi's torso was dressed in a crew-neck T-shirt and sealed in a plastic bag.
The remains were pulled out of the river by a metropolitan garbage trawler at around 10:15 a.m., the MPD said.
The case is being investigated as illegal disposal of a corpse. Police said they will eventually launch a murder investigation.
The torso was bruised across the back, and an initial examination indicated Narumi had been dead for about 10 days. Tattoos across the shoulders suggest affiliation with a crime syndicate, police said.
The remains were contained in a semi-transparent bag approved by the Tokyo Metropolitan Government for garbage disposal, police said.
The garbage trawler does not operate on weekends, and workers said they noticed nothing unusual when they trawled the area Friday.
The torso was found at a spot some 500 meters upstream of the Senju Ohashi bridge and about 500 meters north of JR Minami Senju Station on the JR Joban Line, the MPD said.
Workers spotted the torso as they pulled a net full of garbage onto a conveyor belt.