Police on Saturday were investigating the murder of a 13-year-old boy after his naked body was found with stab wounds beside a river in Kawasaki.

The body of a first-year student, identified as Ryota Uemura, who attended a nearby junior high school, was found at 6:15 a.m. Friday by a passer-by on a bank along the Tama River, near an area of the city where there are several factories and apartment buildings.

An autopsy found that the victim died around 2 a.m. from hemorrhagic shock due to multiple stab wounds to the neck and body. Many of the neck wounds were inflicted by stabbing and slashing thrusts.