When a dog walker and his young son stumbled across two knotted bin bags in the woods by a theme park in 1998, they could never have imagined what lay inside – and the mystery that would leave the nation in the dark for 27 years.

It was 10.45am on March 14, 1998, when a Warrington man walking his dog in the woods near Gulliver’s World theme park in Cheshire saw the bags and poked a hole in them with a stick.

Tragically, he found the lifeless body of a newborn baby boy inside. The child had been suffocated.

The police were soon on the case. But despite searching for the baby’s mother and father, detectives were stumped.

The cops named him Callum after the Callands district of the Cheshire town where he was found dead and a funeral service was arranged by locals for the boy, who was believed to have been born at full term.

He was buried in Warrington Cemetery a few months later. The headstone, paid for with money raised by locals, said: ‘Baby Callum, precious child of God. Laid to rest July 27, 1998. With love, from the people of Warrington.’

Even so, the police kept searching with Callum’s and his mother’s DNA that was found on the bin bags. They found no matches on their system and for decades the case went cold.

But in 2022, everything changed. Police got a match. They knew Callum’s mother was 55-year-old Joanne Sharkey. And when she was arrested, she told her husband: ‘I’m not gonna f***ing deny nothing, it is what it is isn’t it. I f***ing did it’.’

But this week, despite admitting she killed her baby and concealed his birth, a judge let her walk free. 

This is the reason why.

Joanne Sharkey, 55, (pictured) was revealed to be her baby’s killer 27 years after his death in 1998

Pictured: The coffin of her son Callum during his funeral at St Elphin’s Church in Warrington on July 27, 1998

This is the approach road to Gulliver’s World theme park in Warrington, where baby Callum was found

In 1998, Sharkey was a 28-year-old housing benefit officer at West Lancashire Council.

Twenty months before she killed Callum, she gave birth to another son, Matthew, in 1996. 

Both boys had the same father, Joanne’s husband, who is believed to have been married to the killer for 31 years. The couple are still thought to be together. 

During the killer mother’s trial, prosecution barrister Jonas Hankin KC said psychiatrists agreed Sharkey was ‘fearful of becoming a mother to another child’ and developed a depressive illness which ‘substantially impaired (her) ability to form rational judgment and exercise self-control’.

After Matthew’s birth, Joanne Sharkey found the combination of a full-time job and motherhood challenging, and she has since been diagnosed as suffering from postnatal depression during that period.

When she became pregnant again in the summer of 1997, she did not tell her husband and instead kept her pregnancy a secret.

When the baby was born in the bathroom of her house in Croxteth, Liverpool, she heard him starting to make a noise and covered his nose and mouth ‘to make him quiet’. 

On March 12, 1998, a man saw a young woman walking quickly out of the woods near Gulliver’s World in Warrington who looked ‘upset’.

Callum was discovered close to Gulliver’s World theme park in Warrington in March 1998

The people of Warrington held a funeral for the tiny tot. Pictured: The funeral procession for baby Callum at St Elphin’s Church in Warrington on July 27, 1998

The headstone, paid for with money raised by locals, said: ‘Baby Callum, precious child of God. Laid to rest July 27, 1998. With love, from the people of Warrington’

The man walked into the woods and saw a black bin bag lying on the ground to the left of the track but did not touch it.

Two days later, a dog walker saw the same bag, was curious about what was inside and punctured it with a stick to find the body of an infant.

Upon the discovery, he sought help from the theme park and a paediatrician happened to be present, who confirmed the body was that of a baby boy. 

Callum was pronounced dead at 11.25am on March 14.

His body was taken to Warrington General Hospital, where a pathologist found the baby had been a ‘normally developed, full-term infant’ with no structural abnormality or natural disease.

He found a number of bruises over the infant’s face, head and neck, and wads of tissue in his mouth.

Due to findings from a post-mortem, Cheshire Constabulary launched a murder investigation – and a full DNA sample was taken from the baby, as well as from blood found on the bin bags.

This identified the DNA profile of the mother of the baby, but there was no match on the police database for her. 

Joanne Sharkey pleaded guilty to one count of manslaughter on the grounds of diminished responsibility and endeavouring to conceal the birth of a child

A court artist’s sketch of Joanne Sharkey at Warrington Magistrates’ Court on April 16, 2024

Sharkey dabbed her eyes with a tissue and became tearful as she delivered her guilty pleas

On Friday, Sharkey sat shaking with emotion and wiping away tears as the judge said she would pass a suspended sentence

A partial DNA profile for the father was obtained, but there was again no match.

Police said DNA swabs were taken from a large number of people living locally at the time, but none provided a match.

Officers carried out house-to-house enquiries with hundreds of people interviewed, and spoke to local hospitals, midwife services, GPs, other medical services and schools, to identify any women or girls who may had given birth recently.

But despite all the force’s efforts and anniversary media appeals in the following years, nothing led to the identification of Callum’s parents.

It was only in January 2022 that the case was cracked after the DNA of Callum’s elder brother Matthew Sharkey, Joanne’s first child, was uploaded to the national database because he had been arrested for an unrelated offence.

His DNA was found to be a close match to that of the infant. DNA samples were then taken from Joanne and Neil Sharkey, who were identified as the biological parents.

Cheshire Constabulary’s Major Crime Review Team carried out further DNA analysis and identified Callum’s mother and father as Joanne and Neil Sharkey.

The pair were arrested on July 28, 2023, on suspicion of murder, and DNA samples were obtained, which confirmed that they were his parents. Both were later released on bail while enquiries continued.

When Joanne Sharkey was taken into custody she showed little emotion, pointing to a man, thought to be her husband in another room, saying that he knew ‘nothing about this’

Sharkey appeared unsurprised when she was taken into custody by police in 2023

Joanne’s husband was released without facing charges – but the 53-year-old mother from West Derby, in Liverpool, was charged in April 2024 with murder and concealing a birth.

On March 6 this year, Sharkey pleaded guilty to one count of manslaughter on the grounds of diminished responsibility and concealing the birth of a child.

Speaking at the time, Adam Till from the Crown Prosecution Service said: ‘This has been a complex case about a baby whose life was unfairly cut short.

‘He would have been an adult today and it’s devastating to think of the life he could have had. The circumstances of his death have deeply affected everyone who has been involved in this case as well as the wider community.

‘We carefully considered and accepted a guilty plea to manslaughter following a thorough review of the psychiatric reports and medical evidence. 

‘The evidence concluded that Sharkey’s mental state was significantly impaired at the time of the offence due to a medical condition which diminished her criminal responsibility.

‘While the outcome of this case will never bring the baby back, we hope it brings a small measure of comfort to everyone who has been affected by this awful case.’

The CPS said medical evidence concluded that Sharkey had an ‘abnormality of mental functioning’ at the time of the offence ‘arising out of a medical condition’ and this ‘substantially impaired her ability to form a rational judgement and to exercise self-control’.

It was added that this ’caused or was a significant contributory factor in causing her to kill her newborn child’.

This year, Joanne Sharkey admitted that she killed Callum. However, she received a two-year suspended sentence on Friday at Liverpool Crown Court that saw her walk free. 

Despite admitting to killing her own baby, the judge suggested letting her avoid prison was the compassionate thing to do. 

Passing sentence at Liverpool Crown Court, the judge Mrs Justice Eady told Sharkey she accepted her mental state at the time had ‘substantially impaired your ability to form rational judgments’ and since then had been ‘haunted’ by what she had done.

Sharkey sat shaking with emotion and wiping away tears as the judge said she would pass a suspended sentence.

The defendant’s family in the public gallery broke down in tears and exchanged hugs.

Revealing the exact reason the killer did not go to jail, the judge told Sharkey: ‘I’m clear you suffered a lengthy postnatal depression.

‘The events that bring us to this court are both terrible and tragic. Nothing I can do or say can turn the clock back to resolve the tragedy of this case.

‘You lived isolated with this terrible and tragic knowledge. You had carried this with you the whole time, thinking about it every day.

‘I’m satisfied your offending was not planned or premeditated. 

‘I’m satisfied that this very sad case calls for compassion. No useful purpose would be achieved by immediate imprisonment.’