Wrongly Convicted: How flawed forensic evidence branded Sally Clark a 'baby killer'

In this series, 9honey takes a look back at some of the world's most shocking cases in true crime history and the women at the centre who were wrongly convicted.

The call for help was made at 9.35pm. Sixty-five minutes later, he was declared dead.

It was the evening of December 13, 1996 and Sally Clark was at the luxury home she shared with her husband, Stephen, and their healthy newborn son, Christopher. In a matter of hours, the family of three would become a family of two.

Years later, when history repeated itself, Sally was branded a 'baby killer".

The unthinkable dual tragedy

When ambulance officers arrived at the Clarks' Wilmslow home, in the town of Cheshire in England, the solicitor and new mother was in a state of hysteria and shock. She struggled to unlock the front door's deadbolt, unable to find the keys. 

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With Stephen at a work Christmas party, Sally was at home with Christopher. During a moment checking on her beloved 11-week-old, Sally found his tiny frame lying motionless in his Moses basket. She frantically phoned for help.

The cause of Christopher's death was deemed to be Sudden Infant Death Syndrome (SIDS), otherwise known as "cot death".

The Clarks tried for another baby, hoping this would help them come to terms with their grief. In November 1997, the couple's second son, Harry was born.

Like Christopher, Harry was a healthy baby. However, in January 1998, at just eight weeks old, he was found collapsed in his bouncy chair.

Sally had found her son unresponsive, screaming out to Stephen in another room. Attempts to resuscitate him by Stephen and ambulance officers failed.

Distraught at the loss of their second child, the Clarks – both lawyers – urged Macclesfield Hospital, their local hospital, to find a specialist paediatric pathologist to carry out the postmortem examination. 

Yet the same general pathologist who had carried out Christopher's examination was responsible for Harry's postmortem.

Williams' findings were indicative of non-accidental injury, "consistent with shaking on several occasions over several days", with shaking the likely cause of Harry's death.

The findings led to further tests being carried out in relation to Christopher's case, with the pathologist changing his opinion on cot death. Instead, he concluded there was evidence Christopher had been smothered.

A guilty verdict

In February 1998, less than a month after losing their second child, Sally and Stephen Clark were arrested on suspicion of murder. 

Five months later, Sally was charged with the murders of both children. Stephen was not charged. As she awaited trial, Sally gave birth to the couple's third son.

At trial, the prosecution portrayed Sally as a "lonely drunk" who struggled to settle into her new home and role as a mother. They also suggested she was resentful of her children for having to take a career break.

"We were meant to have children and I loved them so much, I couldn't believe it happened twice," Sally told the trial.

The prosecution also relied on the expert evidence of a senior paediatrician, who told the jury the statistical chance of a double cot death was "73 million to 1". It proved damning evidence.

Despite the challenges in front of her, Sally maintained her innocence. 

In November 1999, she was found guilty and given two life sentences. In 2000, Sally's legal team's appeal of the verdict failed.

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The appeal judges accepted the paediatrician's statistics were flawed, with the actual odds of two babies dying of cot death in a family like the Clark's was just one in 77. Yet, the judges were convinced there remained "overwhelming" evidence of her guilt. 

In 2001, Clark was suspended from the Roll of Solicitors.

A wave of support

During her time behind bars, Sally was shown "compassion and understanding" from the prison governor, staff and inmates. She was also sent letters from scores of well-wishes and support of friends. 

Her biggest supporter was her husband, who never wavered in her innocence.

"I wouldn't be human if the thought had never crossed my mind that Sally might have killed our babies, but I dismissed it immediately," Stephen said.

"She is the kindest, sweetest, most caring person I have ever known."

Two years into Sally's sentence, the Royal Statistical Society (RSS) took the unprecedented step of writing to the Lord Chancellor to object to the way the "73 million to 1" statistic had been calculated in her case.

"This figure had an immediate and dramatic impact on all media reports of the trial, and it is difficult to believe that it did not also influence jurors. The calculation leading to 1 in 73 million is invalid," the RSS letter read. 

"It would only be valid if SIDS cases arose independently within families, an assumption that would need to be justified empirically.

"Not only was no such empirical justification provided in the case, but there are very strong reasons for supposing that the assumption is false. 

"There may well be unknown genetic or environmental factors that predispose families to SIDS, so that a second case within the family becomes much more likely than would be a case in another, apparently similar, family."

The RSS stated Sally's case was one example of "a medical expert witness making a serious statistical error".

'Secret' test leads to vindication

In 2003, Sally's conviction was quashed on appeal by a panel of three judges.

During the appeal, the judges were told crucial medical evidence which could have cleared Sally was "kept secret" from her defence team.

The court heard that at the end of 2000, it emerged there was clear evidence in the form of microbiological tests.

The tests revealed Harry had an infection that had spread to his cerebral spinal fluid and in all likelihood he had died suddenly in reaction to the bacteria.

The judges were told the nondisclosure of the evidence led to a "serious miscarriage of justice". They were also told that if the results were presented at trial, Sally would not have been convicted of the murders of Harry or Christopher.

Incredibly, it was Stephen who had discovered the "secret" test buried among 1000 pages of medical notes on his two sons. 

Two years after Sally's conviction, Macclesfield Hospital, under pressure from Sally's solicitor, Marilyn Stowe, had released Christopher and Harry's medical notes. Stowe was working on the case voluntarily.

"In there was a report which seemed to be a blood test," Stephen told The Observer in 2003.

"Now, I remember at trial the jury asking whether or not blood tests had been done on Harry and I seem to remember that the answer from the prosecution was that the tests hadn't been done.

"So I sent this report to one of the doctors who's been helping us behind the scenes and he shouted almost, 'Eureka! – there's a cause of death here'. 

"'There's potentially lethal bacteria in various sites of Harry's body but you need to have it checked by a pathologist,' and so eventually we found Professor Morris in Lancaster and he wrote us a report saying that was the cause of death for Harry, that he wasn't murdered."

'Our nightmare is finally at an end'

In January 2003, Sally was cleared of the crimes. As she took her first steps of freedom she was hugged and kissed by her husband.

"This is not a victory. We are not victorious. There are no winners here," she told the waiting media.

"We have all lost out. We simply feel relief that our nightmare is finally at an end."

In July 2005, the paediatrician who testified was struck off by the General Medical Council (GMC) for giving "erroneous" and "misleading" evidence in Sally's case. A year later, the High Court overturned the GMC's decision.

After being released and cleared, Sally attempted to rebuild her life with Stephen and their son. 

Yet, a path back to normalcy after being wrongly convicted of her sons' murders proved too great. Sally was diagnosed as having serious psychiatric problems and an acute alcohol dependency. She spent time in clinics in an attempt to overcome the problem.

However, in March 2007, Sally was found dead at her home. A coroner ruled her death as an accident. She was 42.

"Sally was unable to come to terms with the false accusations, based on flawed medical evidence and the failures of the legal system, which debased everything she had been brought up to believe in and which she herself practised," the family said in a statement.

"The hope is that some good may come out of the tragedy of her untimely death and that a sense of balance will be restored which will not only protect infants but also their innocent parents."