Olive Durand-Deacon thought she'd met a charming inventor. It was the 'Acid Bath Vampire.'

On a chilly February day in 1949, a meticulously dressed, charming British man named John Haigh walked into a London police station with a concerned female friend to report a missing woman. 

Little did the officers know they were about to uncover one of Britain's most horrific serial killers — a man who believed dissolving his victims in acid would make him untouchable by the law.

A high-society London gentleman turned serial killer.

Dressed in expensive suits, Haigh posed as one of the city's distinguished gentlemen. Image: Getty

John George Haigh looked nothing like what you'd imagine a serial killer to be. 

Impeccably dressed in high-end suits, he was cultured, charming, and moved comfortably through London's high society. He enjoyed classical music, drove luxury cars, and resided in expensive hotels.

Born in 1909 to strict Plymouth Brethren parents who built a seven-foot fence around their Yorkshire home to keep out "worldly influences," Haigh's childhood was reportedly bleak and isolated. 

His parents told him biblical stories about sin and damnation, setting the stage for what would become a disturbed adulthood.

After failed attempts at legitimate work and marriage, Haigh turned to fraud and forgery, spending significant time in prison. 

It was behind bars where he first experimented with sulphuric acid, observing how it dissolved mice completely, per New Scientist. 

This sparked a dangerous idea that would become his murderous signature.

A thirst for blood — and money.

Between 1944 and 1949, Haigh murdered at least six people. His victims included:

• William Donald McSwan, a former employer

• Donald and Amy McSwan, William's parents

• Dr. Archibald Henderson and his wife Rosalie

• Olive Durand-Deacon, a 69-year-old wealthy widow

His method was always the same — gain trust, lure victims to his workshop, kill them (either by bludgeoning or shooting), then dissolve their bodies in drums of concentrated sulphuric acid. 

After the bodies had fully dissolved into a sludge, he would pour the remains down drains or onto nearby waste ground.

But Haigh's motivation wasn't some psychopathic compulsion — it was cold, calculated greed. Through forged documents, he assumed his victims' identities, selling their possessions, collecting their pensions, and transferring their assets to himself. 

From the McSwan family alone, he made approximately £4,000, a substantial sum in post-war Britain.

The fantasy that became his downfall.

Olive Durand-Deacon was a wealthy widow. Image: Getty

"No body, no crime". This was Haigh's firmly held belief. He was convinced that without a corpse, police couldn't prove murder. This misguided legal theory would ultimately be his undoing.

When Olive Durand-Deacon went missing in February 1949, suspicion quickly fell on Haigh. 

Mrs. Durand-Deacon was a wealthy widow, who had come across Haigh at a pricey London hotel, according to The History Press. 

She was charmed by Haigh, who invited her to view an invention he was working on at his workshop. She was never seen again.

Haigh's offer to accompany her friend to the police station struck officers as odd, particularly Sergeant Lambourne, who found his overly helpful demeanor suspicious.

When police searched Haigh's dilapidated workshop in Crawley, they discovered rubber gloves, an apron, gas mask, and empty carboys of acid. More damning was the recently fired revolver and a dry-cleaning receipt for a fur coat matching the missing woman's.

Though Haigh confidently told detectives, "How can you prove murder if there's no body?", forensic science was about to prove him catastrophically wrong.

The forensic science: How John Haigh was caught.

The Crawley workshop where the murders took place. Image: Getty

Home Office pathologist Dr. Keith Simpson was called to examine Haigh's Crawley workshop and the sludge outside. Despite Haigh's belief that acid would destroy all evidence, Simpson quickly spotted a gallstone in the residue, something that wouldn't dissolve in acid.

Further examination and forensic science revealed 28 pounds of human body fat, fragments of bone, part of a left foot, and most crucially, Mrs. Durand-Deacon's complete dentures. The meticulous detective work also uncovered her lipstick container, a handbag, and a hairpin.

When confronted with this evidence, Haigh confessed to all six murders but attempted to avoid the gallows by claiming insanity. He declared he was a vampire who drank his victims' blood before dissolving their bodies, a last-ditch attempt to be sent to Broadmoor psychiatric hospital rather than face execution.

The final act: Wandsworth Prison execution.

John Haigh was executed at Wandsworth prison. Image: Getty

The jury took just 15 minutes to find Haigh guilty. Soon, he became known as the 'Acid Bath Vampire'.

Before his execution, he welcomed Madame Tussauds staff into his cell so they could make a life mask for a wax figure they would display the day after his death, even donating his own clothes for the exhibit.

On August 10, 1949, John Haigh was hanged at Wandsworth Prison, bringing an end to one of Britain's most notorious serial killers. His case remains a landmark in British criminal history and forensic science, proving that even when a killer tries to erase all evidence, justice can still be served.

His story was later turned into the thriller film A Is For Acid.

Image: Getty.