Kaspar Hauser (30 April 1812 – 17 December 1833) was a German youth who claimed to have grown up in the total isolation of a darkened cell.

Theories propounded at the time identified Hauser as a member of the grand ducal House of Baden, hidden away because of dynastic intrigue.

[1] In 2024, a scientific study ruled out Hauser's princely descent by comparing mitochondrial DNA haplotypes with the House of Baden.

On 26 May 1828, Kaspar Hauser, then a teenage boy, was found wandering the streets of Nuremberg, then part of the Kingdom of Bavaria, carrying two letters.

Its heading read: daß Orte ist unbenant 1828 "From the Bavarian border The place is unnamed The anonymous author of this letter said that he had assumed custody of Hauser as an infant on 7 October 1812.

While being examined by police, Hauser showed familiarity with money and the ability to say some prayers and a small measure of reading.

[4] Hauser spent the following two months in Luginsland Tower in Nuremberg Castle, in the care of jailer Andreas Hiltel.

Contrary to many later accounts, observers described Hauser as being in good physical condition and able to walk well; for example, he could climb over ninety steps by himself to his room.

Paul Johann Anselm Ritter von Feuerbach, president of the Bavarian court of appeals, began to investigate the case.

As Feuerbach told the story, "When Professor Daumer held the north pole [of a magnet] towards him, Kaspar put his hand to the pit of his stomach, and, drawing his waistcoat in an outward direction, said that it drew him thus; and that a current of air seemed to proceed from him.

As was obvious from his blood trail, Hauser at first fled into the house to the first floor, then went downstairs and climbed through a trap door into the cellar.

Alarmed officials called for a police escort and transferred Hauser to the care of Johann Biberbach, a municipal authority.

Skeptics believed that Hauser had deliberately cut himself with a razor, then left it in his room on the first floor before hiding in the cellar.

"[12] Having outstayed his welcome in the Biberbach household, the town of Nuremberg transferred Hauser in May 1830 to the house of Baron von Tucher.

In December 1831 he transferred Hauser to a schoolmaster named Johann Georg Meyer in Ansbach, under the patronage of Anselm von Feuerbach.

When a policeman searched the Court Garden, he found a small violet purse containing a pencilled note in Spiegelschrift (mirror writing).

Inconsistencies in Hauser's account led the Ansbach court of enquiry to suspect that he had stabbed himself and then invented a tale about being attacked.

"[28] Leonhard rejected the views of both Heidenreich and Hesse, contending that:"Kaspar Hauser was, as other authors already opined, a pathological swindler.

His parents were Charles, Grand Duke of Baden and Stéphanie de Beauharnais, a cousin by marriage and the adopted daughter of Napoleon Bonaparte.

Disguising herself as a ghost, the so-called "White Lady", she sneaked into the nursery of the infant prince, kidnapped him and replaced him with a dying baby.

[29] In his Historical Mysteries, Andrew Lang summarises the results:"It is true that the Grand Duchess was too ill to be permitted to see her dead baby, in 1812, but the baby's father, grandmother, and aunt, with the ten Court physicians, the nurses and others, must have seen it, in death, and it is too absurd to suppose, on no authority, that they were all parties to the White Lady's plot.

"[30] Historian Fritz Trautz went so far as to write that, "The silly fairytale, which to this day moves many pens and has found much belief, was fully disproved in Otto Mittelstädt's book.

[32] In November 1996, the German magazine Der Spiegel reported an attempt to genetically match a blood sample from underwear thought to have been Hauser's.

This analysis was performed in laboratories at the Forensic Science Service in Birmingham, England, and the LMU Institute of Legal Medicine at the University of Munich in Germany.

[33][34] In 2024, a new study corroborating previous analysis by massive parallel sequencing ruled out the prince theory by demonstrating that the mitochondrial DNA haplotypes in all samples attributed to Hauser including the previously examined blood sample were identical and different from the mitochondrial lineage of the House of Baden.

[39] It alludes to the works by Verlaine and Wassermann, and has been called the "most striking" expression of a literary trope in which Kaspar Hauser "stood for the natural, poetic genius lost in a strange world, lacking a home, a sense of origin and attachment, and fearing a violent but uncertain future.

"[42] In 1994, the English poet David Constantine explored the story and its personae in Caspar Hauser: A Poem in Nine Cantos.

In this modern western-like re-interpretation featuring Vincent Gallo, a music-obsessive Kaspar washes up on a Mediterranean beach, where half a dozen protagonists try to make sense of who he is.

[52] In his later years, Paul Johann Anselm Ritter von Feuerbach took a deep interest in the fate of Kaspar Hauser.

[55] In a "Kaspar Hauser experiment", a nonhuman animal is reared isolated from members of its own species, in an attempt at determining which behaviors are innate.