A 25-year-old man was arrested in connection with last week's discovery of the burnt bodies of a man and a woman on a riverside north of Tokyo, police said Sunday.

They said Ryoken Hirayama, who turned himself in at a police box in Tokyo on Wednesday, is being questioned on suspicion of damaging the corpses by setting them on fire, in possible collusion with others, at the site in Nasu, Tochigi Prefecture, near a resort hotel and a golf course.

The bodies, which were noticed on Tuesday morning by a passerby, had their hands and feet bound, and their heads were covered in what appeared to be plastic bags and wrapped in adhesive tape, according to investigative sources.

They were believed to have been abandoned and set on fire between the wee hours of Tuesday and the time they were discovered.

One of the bodies was identified as that of 55-year-old man Ryutaro Takarajima, whose address and occupation are unknown, while the other body is believed to be his wife, estimated to be between 40 and 60 years old, police said. Both died of suffocation.

Photo taken on April 18, 2024, shows the spot where two burnt bodies were found in Nasu, Tochigi Prefecture.(Kyodo)

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2 burnt bodies found on riverside north of Tokyo