The Karin Case: the Hornsö Rappings of Karin Nauckhoff

Hornsö lies in Småland, in Kalmar County, among the forests between Högsby, Nybro and Mönsterås. The forest manager's residence there was a large, remote villa. It was already known as a spökhus. A haunted house.

Its new mistress was Karin Nauckhoff, born Karin Segerdahl in 1877. Her husband Fredrik was the jägmästare, the state forest manager. Karin had a history of anxiety, fainting spells and depression, and an interest in the supernatural. She disliked Hornsö and wanted to move to Kalmar. At an earlier séance, working with a spritglas, the Swedish glass and letters board, she had made contact with an entity that called itself Piskator.

Spring 1904. An unexplained knocking began in the walls and floors, followed by the sound of footsteps. Questions were put to the sounds, and they answered by means of coded raps. The raps "oscillated in strength from heavy blows, as from a hammer, to sounds so weak that they could hardly be caught with certainty." Piskator, it seemed, had found a voice.

Fredrik and several others heard it often. According to the account later published in English, every possible precaution was taken to rule out normal explanations. On 5 September 1904 the newspaper Kalmar carried the story.

Local tradition remembers more. Knocking so strong the whole house shook. Doors opening and closing with nobody nearby. Things floating in the air. Those details come from later retellings, not from the investigators' reports.

The physician and psychotherapist Poul Bjerre came to Hornsö with his friend and colleague Hjalmar Wijk. They stayed in the villa for a long period. Under hypnosis, Bjerre could make the knocking happen on command, and could ask Piskator for a set number of raps. As Karin's anxiety was calmed, the phenomena grew weaker.

Then Piskator gave an instruction. Dig at a certain spot in the cellar. Bjerre dug. He found bones. They turned out not to be human.

Bjerre and Wijk concluded that the phenomena were tied to Karin and caused by what they called her hysterical disposition. Bjerre believed the raps came from her heartbeat, carried by a nerve force. He later suggested that Karin had found the bones when they moved in, feared they were human, and produced the knocking unconsciously. Nobody accused her of deliberate fraud. In 1905 Bjerre published Fallet Karin, treating the case as a matter of mental health rather than spiritism. Wijk's English account, "Karin: An experimental study of spontaneous rappings," appeared that year in the Annals of Psychical Science.

Not everyone agreed. The Uppsala psychologist Sydney Alrutz held his own sessions in 1905. He reported raps, levitating objects and apports, and presented them as genuine spirit manifestations. Bjerre visited in August 1905 and wrote that Alrutz had "destroyed everything," above all Karin's nerves. The quarrel spilled into books, letters and newspapers.

Bjerre returned to the case in Spökerier in 1947 and still held to a psychological explanation. In 2005 the sceptics' journal Folkvett called it unremarkable as a phenomenon, yet still Sweden's most famous poltergeist outbreak. The SPR Psi Encyclopedia uses Karin as its example of responsive rapping. The house later passed to IOGT-NTO, and it has been privately owned since 2018.