The torso of an adult male was found in a bag at a park in Tokyo's Sumida Ward early Wednesday morning, police said.
Police said a 50-year-old man who sleeps in the park notified them of a suspicious bag at around 1:10 a.m. When officers looked inside, they found the torso wrapped in three semitransparent garbage bags.
Police are treating the case as one of murder, mutilation and dumping of a corpse. The torso had sustained five stab wounds -- three to the back, one in the left part of the chest and another in the left hip. The cause of death was determined to be excessive blood loss.
Investigators said they were trying to find the head and limbs in order to establish the victim's identity.
According to sources, the victim is believed to have been in his 20s to 40s, and his blood type was AB. The time of death was tentatively put at around 24 to 48 hours prior to the discovery of the torso.