Peter Kürten's crimes were so unspeakable that doctors cut open his head to find out what drove his insatiable sexual bloodlust.

But they found no abnormalities in his brain to explain why the 'Vampire of Dusseldorf' brutally murdered at least nine people and drank their blood.

Today his head, split down the middle, is on display in the unlikeliest of places, far from his home in western Germany where he was beheaded in 1931.

Hanging from a rotating hook and mummified in a gruesome expression, the face of evil is one of many attractions at Ripley's Believe It or Not in Wisconsin Dells.

The 48-year-old confessed to 70 crimes when he was finally caught including rapes, murders and arson against women and girls as young as four.

He claimed to derive intense sexual pleasure from the sight of blood and death and would stab or bludgeon his victims until he reached orgasm.

Hanging from a rotating hook and mummified in a gruesome expression, the head of serial killer Peter Kürten is one of many attractions at Ripley's Believe It or Not in Wisconsin Dells

Kürten could have committed dozens more murders if he hadn't been jailed twice for arson, desertion, robbery, fraud, and burglary.

His first confirmed murder was of nine-year-old girl Christine Klein he found sleeping during a break-in, strangled her and slashed her throat with a pocket knife.

The next day he returned to the tavern to listen to people vent their outrage at the murder, and visited the girl's grave to pleasure himself over it.

Months later he killed Gertrud Franken, 17, in the same way before he was jailed for a string of burglaries and arsons.

After his release in 1921 he stabbed, strangled and bashed to death with a hammer numerous other men, women, and girls.

Some of his victims survived, often because the sight of them bleeding was enough to satisfy his depraved sexual desires, but none could identify him.

He even sent letters with the location of where he buried one of his victims to the police to taunt them.

On one occasion he met two sisters aged five and 14 and bribed the older one to fetch him some cigarettes while he strangled and slashed the younger girl's throat.

When the older sister returned he stabbed her before biting her throat and sucking the blood from her neck.

Kürten's killing spree finally came to an end when he made a sloppy mistake in a savage attack on a young woman on May 14, 1930.

Maria Büdlick, 20, was trying to escape the unwanted attention of a man who followed her after she got off a train, and Kürten intervened.

After telling the man to leave, he persuaded Ms Büdlick to come with him to his house to eat, but she declined to sleep with him.

He offered to take her to a hotel but instead lured her into the woods where he raped and choked her before letting her go.

The traumatised woman didn't tell police but wrote it down in a letter to a friend. However, she mailed it to the wrong address and postmen gave it to the police.

Kürten let Ms Büdlick go after she lied to him that she couldn't remember his address, and she was able to lead police to his home.

The killer spotted them and left without being detected, but he knew his time was up as they now knew his identity.

Kürten confessed to 70 crimes when he was finally caught including rapes, murders and arson against women and girls as young as four

Kürten confessed his crimes to his wife, who knew nothing of his double life a serial killer, just about his other misdeeds.

He told her to turn him in to collect the reward for the Vampire's capture and he was arrested at gunpoint nine days after attacking Ms Büdlick.

Despite confessing to all the murders he was charged with and claiming responsibility for many more, he pleaded insanity at trial.

There he detailed his shocking list of victims and his sexual desire for blood, admitting to having no conscience or remorse.

More detailed interviews with psychologist Karl Berg formed the basis of an appropriately-named book, The Sadist.

A jury took less than two hours to convict him of nine murders and seven attempted murders and he was executed on July 2, 1931, after a last meal of sausages, fried potatoes and two bottles of wine.

'Tell me... after my head is chopped off, will I still be able to hear, at least for a moment, the sound of my own blood gushing from the stump of my neck?' he asked as he was walked to the guillotine.

'That would be the pleasure to end all pleasures.'