The search for a 13-year-old missing boy led police to a terraced house at a French villa in the old town of Tarascon, near Marseille, where they found his body badly mutilated inside a bag.

French media identified the deceased as Romain, who was reported missing from his foster home after he reportedly paid a visit to his mum who lives in the villa on Friday. His body was later found on Sunday, after neighbours complained of "a terrible smell" coming from the house.

A cleaner who entered the property found the teenager's chopped-up body, including his partially-eaten head, placed inside a bag. Strips of flesh were ripped from his shoulders, fueling speculations of cannibalism. Officers on the scene reportedly also discovered satanic objects inside.

''We went into the bathroom. Romain was beheaded and his upper body wrapped in plastic. I don't know how you can do that to a child. It's inhuman," the 29-year-old housekeeper told Parisien.

Local public prosecutor Laurent Gumbau said on Monday that the boy's body was so badly dismembered that it can only be identified by a DNA test. Authorities then tracked the owner of the house which led them to a 32-year old man named Arthur A.

Neighbours reported that the alleged murderer escaped the apartment over the rooftops. But the police eventually found him three hours later at another location in Tarascon. He was shot down dead after he threatened officers. But Gumbau said that the suspect did not appear to have been armed at the time of his death.

The man was reportedly recently released from a mental health facility and has a history of convictions for acts of violence. He had been living in the apartment in Tarascon since his father died from cancer and since his mother left 15 years ago. The cleaner who discovered Romain's mutilated body expressed disbelief that Arthur A. is capable of such a gruesome crime because he "seemed totally normal."

Police have now opened an investigation into the motive of the murder. They have also ordered an autopsy report for both Romaine and Arthur A.

Crime Scene
Representational image Photo: MANDEL NGAN/AFP/Getty Images