Tochigi Prefectural Police on Sunday arrested a 25-year-old man for allegedly disposing of corpses in connection with last Tuesday’s discovery of two charred bodies on a riverbed in the town of Nasu, Tochigi Prefecture.

Police had been questioning the man, identified as Ryoken Hirayama, voluntarily since Wednesday, when he turned himself in at Tokyo’s Gotanda police station, indicating his involvement in the incident. Hirayama, a construction worker from Koshigaya, Saitama Prefecture, has told investigators two other people were involved.

The man had told police that he let the two people found in Nasu borrow his car. Police have confiscated a black car and are investigating whether bloodstains or fingerprints had been left there.