German police have arrested a teenager suspected of killing his nine-year-old neighbour, after a nationwide manhunt.

Police began searching for Marcel Hesse after the dead boy was found in his home, in the western city of Herne, on Monday night. They said he posted images of the body online.

The teenager, 19, was arrested in Herne on Thursday after identifying himself at a restaurant, German media report.

He then reported a fire in a nearby flat, where another body was found.

He is alleged to have boasted in an online chat-room about also murdering a woman. The body found on Thursday was male, a police spokesman said.

Shocked locals have been gathering outside the apartment in Herne.

The nine-year-old boy died of multiple stab wounds, and the discovery of his body on Monday sparked a huge manhunt.

On Wednesday, with the suspect still at-large, children in Herne were told to play indoors at kindergartens. Police warned the public that the teenager may be armed.

A witness said Marcel Hesse had revealed his attack on the messaging service WhatsApp. He had suggested he had wanted to kill himself but failed and murdered the boy instead.

Police said he shared images on the internet of himself next to the dead child.

The boy’s family told German media that the teenager had asked him to help with a ladder. The boy’s stepfather went to search for the boy, and found his body in Mr Hesse’s cellar.

Investigators in the nearby city of Bochum said the suspect had also spoken online of killing a woman, claiming she “put up more of a fight than the child” and weighed some 120kg (19 stone).

The motive for his alleged attack appeared to have been the woman’s bank, computer and phone details.