Four teenage boys were trespassing on an aristocrat's property when they found a human skull hidden in a tree.
WARNING: This article contains details readers might find distressing.
It was April 1943 and Britain was in the midst of World War II, enduring near-nightly air raids and tough food rationing.
The boys had crept onto the Hagley Estate in Worcestershire to hunt birds and raid their nests to help put food on the table.
But when Bob Farmer climbed into the creepy limbs of an elm tree, he realised that what he thought was an egg was actually a woman's head.
"There was a small patch of rotting flesh on the forehead, with lank hair attached to it. The two front teeth were crooked," he would later recall.
The terrified boys, fearing retribution for trespassing and uncovering a potential murder, made a pact of silence.
But the youngest boy could not keep the secret for long, confessing to his father what they found in the Hagley Woods.
Police descended on the property and found, in a hollow of a massive tree trunk, a woman's skeletal remains was hidden.
There were few clues for authorities to go on, except for some scraps of the woman's clothing and a fake gold wedding ring.
But the mystery took a strange turn when a message was scrawled on a wall in Birmingham in the middle of the night.
"Who put Bella down the wych elm?" it read.
The case became one of Britain's greatest unsolved mysteries. Similar messages occasionally appear around Birmingham to this day.
Some locals believe the killing was ritualistic and points to witchcraft, while others insist the woman was a German spy who was murdered when her mission behind enemy lines went wrong.
The theories as to what may have happened are as bizarre as the local legend is enduring.
Eighty years after she was discovered in a tree in Hagley Wood, the central question remains: Who was 'Bella', and who killed her?
The mystery woman found in the wood
The forensic biologist who examined the woman's body in 1943 remained haunted by the mystery for the rest of his life.
In 2014, when Dr John Lund was 101 years old, he gave an interview to the BBC about the scant clues left behind by the killer.
"It was an excellent place to hide a body," he said of the tree on a remote private property.
Due to the state of her remains, the authorities concluded that the woman had likely died 18 months before she was discovered.
"She was about 35, her front incisors were slightly overlapping, she might have had a baby, but the evidence was not conclusive," he said.
Dr Lund said he and his colleagues believe she was placed inside the tree very soon after her death because rigor mortis would have made it impossible to get her into such an awkward spot.
A piece of peach-coloured taffeta ripped from her skirt was found in her mouth, suggesting she may have been suffocated.
This has given rise to the theory she may have been murdered but there is some debate over this conclusion.
The four boys who discovered the woman's body said they had wrapped some cloth around a stick and wedged into her mouth when they put the skull back.
Even with the victim's distinct teeth, police were never able to figure out her identity.
Resources were depleted due to the war effort and forensic methods available to officers at the time were crude at best.
While the description of the victim's body was compared to thousands of missing persons cases across the region, officers could not find a match.
And a DNA test to finally solve the mystery once and for all is no longer an option, according to Dr Lund.
"As far as I know, we gave the body to the university and then the bones mysteriously disappeared," he said.
The West Midlands police have since confirmed they don't have her body.
In a statement to a local newspaper in 2018, a spokesperson revealed they can find "no documentation, that may relate to this case at either of the West Midlands Police Museums".
Ominous missives and false leads
Despite the strange circumstances surrounding Bella's death, the case soon faded from the minds of Hagley's residents preoccupied with World War II.
But someone was determined not to let her memory rest.
Six months after the woman's body was found, a missive asking who put 'Bella" in the wych elm appeared on an abandoned building near Hagley Hall.
The ominous chalky letters provided authorities with their first potential clue on the woman's identity.
Her name was Bella.
Rumours swirled over whether the scrawled letters may have been written by the murderer or an ex-lover.
But, like so much else with the investigation, the name soon proved a dead end and the case went cold.
Ten years passed before a local journalist, Wilfred Byford-Jones, using the nom-de-plume of Quaestor, wrote a series of sensationalist articles about the tragedy in the wood.
The renewed publicity appeared to have paid off when a new lead came forward.
A woman who called herself Anna sent the local paper, Wolverhampton Express and Star, a letter suggesting "the one person who could give the answer is now beyond the jurisdiction of earthly courts".
"The only clues I can give you are that the person responsible for the crime died insane in 1942 and the victim was Dutch and arrived illegally in England about 1941. I have no wish to recall any more," she went on to write.
The letter was forwarded on to local authorities, who encouraged "Anna" to step forward and discuss the case.
Byford-Jones claimed he was sworn to secrecy about the meeting that took place between himself, the police and Anna.
But five years later, he wrote an account of what happened one rainy night at the Dick Whittington Inn in Kinver.
The article mentioned trapeze artists, spies, munitions and aircraft factories and a desperate chase for Anna among of sea of girls in the inn — but it's not clear how much of the account was true.
Authorities did, however, take a statement from an Una Hainsworth, who offered up some striking similarities to the journalist's story.
Hainsworth told police she was the Anna mentioned in the newspapers and recalled her husband, Jack Mossop, coming home "white and agitated" one night "in either March or April 1941".
He told her he had been at the Lyttleton Arms with a 'Van Ralt' and a 'Dutch piece' — presumably Bella — who passed out in the car on their way home.
Van Ralt apparently told Hainsworth's husband to drive to the wood and the pair stuck the woman in the hollow tree believing she would come to her senses the next morning.
But Bella never woke up and Hainsworth's husband went insane, apparently haunted by the image of the woman in the wych elm.
He died in a mental hospital in 1942, a year before Bella's body was discovered.
Wartime espionage or an occult ritual?
Former Birmingham councillor Peter Douglas Osborn has been following the Hagley Wood case since the 1970s.
He first came across the story after hearing about it from his father, the late squadron leader William Douglas Osborn, who was tasked with guarding the murder scene when the remains were found.
"He took me up to show me the site and [pointed to] this big tree trunk, with a hollow [in] the middle, and said 'that's where the spy's body was found," he told the ABC.
"It was all very exciting to a young child. But subsequently, he clammed up about it."
The idea the woman may have been a spy is another odd twist in the case.
The theory goes that Bella may have been linked to a German spy ring operating in Birmingham on a vague mission of cross-country espionage.
There were munitions factories scattered across the Midlands at the time and knowledge about these locations may have been valuable to England's enemies.
What may have started as a local rumour was given prominence in Byford-Jones' account of his meeting with Anna in 1953.
The journalist claimed Anna told them the woman was part of a group of pro-German conspirators who were working with her husband to obtain intelligence about weapons and aircraft munitions in the West Midlands.
The mystery deepened years later when the UK spy agency MI5 released its wartime files on an enemy agent named Josef Jakobs, who parachuted into Cambridgeshire in 1941.
He was discovered by farm workers walking in a nearby field and handed over to police.
In his pocket, he carried a photograph of a young woman who was later identified as singer and actress Clara Bauerle.
The links between Clara and the woman in the wood are murky.
Some claim Clara was working as a spy and may have parachuted into the Hagley area during the war, which is how she ended up in the hollow tree.
But no parachute was found at the crime scene, disproving the theory.
Mr Osborn is among those who believe the woman's body is part of a tangled web of spies and intrigue, though he goes on to acknowledge the case endures because it is open to interpretation.
"If you look at the intelligence gathering services at the time, on both sides, they weren't particularly good," he said.
"Agents were sent in all sorts of directions, to the island, whether they were a complete failure [or not] ... obviously, there was no skill to it, it was just almost amateur in the way that they collected information."
Author James Hawyood said there was at least one spy who was operating in the Birmingham area during WWII, but he was captured immediately.
"It's an area where spies would want to be active but there doesn't seem to be any evidence that connects the woman in the tree to espionage at all and it seems a rather odd way to dispose of a dead spy …," he told the BBC.
Meanwhile, supernatural explanations have also plagued the case.
The body was reported to have been found in a wych elm — though Mr Osborn says she was found in another type of tree— a tool used to ward off evil in old wives tales.
The name Belladonna is used for the Deadly Nightshade, which has been linked to witchcraft since the middle ages.
Speculation has also focused on the scattering of bones found near the woman's body, which police have suggested was the result of wild animals.
Bella's hand — which some reports claim was severed, though this is disputed — was discovered near her body, convincing renowned archaeologist and anthropologist Margaret Murray the case had the hallmarks of witchcraft.
She reportedly travelled to the Midlands in the 1950s to investigate another crime with suspected occult origins — the murder of farmer Charles Walton, who was stabbed and pinned to the ground with a pitchfork — before hearing about the Hagley Wood case.
In his book, The Case That Foiled Fabian: Murder and Witchcraft in Rural England, Simon Read recalls a conversation between the professor and a local reporter in which she summed up her theory.
"The very act of placing a body in the hollow of a tree is associated with witchcraft," she is quoted as saying.
"The cult of tree-worship is an ancient one and it is linked with sacrifice."
The occult theory was a popular one and endures to this day, but Read believes it is something of a red herring and overlooks the true tragedy of the crime.
The most likely explanation, he concludes, is that "Bella died at the hands of a sadistic killer who knew nothing of witchcraft or black magic".
One of England's greatest murder mysteries
Part of why the Hagley Woods mystery has endured for so many years is due to the sporadic outbreaks of graffiti across the Midlands that continue to ask: Who put Bella in the wych elm?
Police believed the initial missives were all written by the same person, but they have never been identified.
Was it Bella's murderer? An ex-lover? A neighbourhood kid playing a prank?
According to the Evening Dispatch on March 30, 1944: "The writing was too high on the wall to have been done by boys, and the police are inclined to the view that it is the work of someone coming into the city early in the morning with farm produce."
More recent outbreaks are likely the result of copycats.
As for the residents of the village of Hagley, Mr Osborn said they are "not too bothered" by a murder that happened 80 years ago.
"There's absolutely nothing that is proven. I just hope one day it will be resolved," he said.
In 2014, the BBC asked a group of researchers at Queen Mary University in London whether statistical reasoning could help solve the mystery of who put Bella in the wych-elm.
Given the number of hypotheses, and related pieces of uncertain information, the team settled on using a probabilistic technique called a Bayesian Network.
The model found it was 99 per cent likely the cause of death was criminal and 97 per cent likely Bella was not British.
The researchers list a number of caveats with their methods, but ultimately the report found a 33 per cent likelihood that Jack Mossop was involved in her death — and 7 per cent that it was some intelligence service.
It gave the possibility that Bella was a spy 25 per cent, and 16 per cent that she was a sex worker.
There was hope back in 2018 that the mystery would finally be solved after an expert with experience rebuilding people, recreated Bella's features and finally put a face to the name.
The photograph was published with the belief it could find a match among a pile of lost memories and photographs buried in an attic.
No-one stepped forward and the case was officially marked as unsolved in 2005.
The search for Bella and her killer continues.
