How a donated mind helped catch a double killer: Ian Stewart thought he had bought away with homicide TWICE… however an important error led to his downfall

‘My wife had a fit, she’s in the garden,’ a tearful Ian Stewart told emergency operators during an emotional 999 call in the summer of 2010.

At the age of 47, Diane Stewart was believed to have suffered an epilepsy-related death at her home in Hertfordshire. 

Despite not suffering from a fit in 18 years, her sudden death was later ruled to be  unsuspicious by an inquest.

It would take 12 years to uncover the truth of what really happened to the beloved school secretary on that fateful day.

In 2016, Stewart strangled his second partner, Helen Bailey, before leaving her body in the cesspit of their sprawling £1.5million home in Royston, Hertfordshire.

Helen, a celebrated children’s author who wrote the popular Electra Brown book series, lay undiscovered with her dead miniature dachshund Boris for three months until police discovered her.

When Stewart was convicted of Helen’s murder, alarm bells were raised by police about the death of his wife Diana seven years earlier –  and her ‘1 in 1000’ fatal epileptic fit.

In a desperate bid to try and get away with his crime, Stewart claimed in court that he had returned home to find his wife collapsed in the garden and made a desperate attempt to ‘save her life’ with CPR.

Stewart had opted for Diane’s body to be cremated, but her brain was donated to medical science.

The decision was made with Stewart’s blessing – an error that would see him later convicted of her murder.

Following an extensive re-examination of Diane’s brain tissue, consultant neuropathologist Professor Safa Al-Sarraj discovered that Diane had suffered brain changes that were consistent with early ischemia, rather than an epileptic fit.

Defined by the acclaimed expert as ‘damage to the cells due to a lack of oxygen and blood supply’, it ultimately suggested that she likely died as a result of ‘restricted’ breathing ‘for 30 minutes plus’.

Consultant neuropathologist Dr Kieren Allinson also uncovered ‘no positive evidence of a recent seizure’. 

However, he added that he could not rule it out to be SUDEP (a Sudden Unexpected Death in Epilepsy).

It was these groundbreaking scientific findings that would help lead to Stewart’s conviction, more than 12 years after the event. 

In February 2022, Stewart was found guilty of murdering Diane at their home in Bassingbourn, Cambridgeshire. He was later given a whole-life order.

At Huntingdon Crown Court, Mr Justice Bryan described Stewart’s feigned 999 call as ‘harrowing’ and ‘a charade from start to finish.’

In the years that have followed, the Stewart case has raised numerous questions about how the post-mortem examination of a brain really works and what the potential signs are of a suspicious death.

According to acclaimed former forensic pathologist Dr James Grieve, patterns of ‘neurology changes’, ‘blood pressures changes’ and even ‘tiny scars’ or ‘brain injuries’ could serve as possible indicators.

The Scottish-based expert, who undertook more than 550 post-mortem examinations a year, added that one will ‘look for patterns and distributions of neuronal changes or if someone has suffered a significant brain injury such as a cerebral haemorrhage’.

‘Other things include blood pressure changes to the blood vessels or a tiny scar or tiny tumour,’ he told The Daily Mail.

‘It is of course also case dependent and highly dependent on things such as circumstances, past medical history and other factors,’ he added.

‘But, by the time you do the autopsy, you should have a very good idea of what you’re expecting to find.’

Dr Grieve noted that the specialist beta-APP staining technique could be applied by neuropathologists to help them recognise changes and patterns to the brain.

Often used in homicide investigations, the technique can help to indicate whether a brain injury, such as a head trauma, shaking or blunt force, has occurred within an estimated 35-60 minutes before death.

Explaining the challenges of brain examination further, he said: ‘The difficulty in examining a fresh brain is that the consistency of a brain is like jelly, which means it is quite difficult to cut. By no means impossible, but it takes a little bit of skill and care.’

Yet despite these potential challenges, he stressed that the brain ‘is a terribly important and vital organ’ that must be examined carefully in cases where there are believed to be ‘subtle changes’ or abnormalities. 

‘If you fail to look inside the head you’ll never truly know how somebody could have died. In some cases it might not matter, but in this case (the Stewart case) it was key.’ 

Dame Professor Dawson, head of the Centre for Forensic Soil Forensic Science at the James Hutton Institute, told the Mail: ‘The particular significance of the Diane Stewart case was that it showed how evidence preserved for medical, not forensic, reasons can later become pivotal in a criminal investigation.

‘The examination of her brain provided objective, scientific proof of poisoning that could not be explained away and ultimately overturned as an apparent natural death.’

While the reason for Stewart’s heinous crimes can never be truly understood, judge Mr Justice Simon Bryan declared during Diane’s trial in 2022 that he was ‘satisfied that the major motive for her murder was for financial gain’.

The killer received £96,607.37 after Diane’s passing from life insurance pay outs and her savings, while he also stood to gain £1.8 million in the event that Helen, should die.  

Stewart had first met Helen, the daughter of a public health inspector and originally from Northumbria, whom he had got in touch with through an online bereavement group as he ‘grieved’ over the death of his first wife Diane a year prior.

Helen, meanwhile, had lost her husband John Sinfield when he drowned in front of her on a holiday to Barbados, had coped with her grief by writing about it.

Her blog Planet Grief was turned into a successful book, When Bad Things Happen In Good Bikinis, serialised in The Daily Mail. 

Within two years of Stewart making contact with Helen, the couple had sold their respective homes and together bought a stunning Arts and Crafts house with an outdoor pool and acre of land in Royston, Hertfordshire. 

Believing Stewart to be her ‘happy ending’ – and with her writing career in the ascendant – Helen believed she had finally found contentment, yet shortly after he would strangle her. 

Stewart denied the murder of his wife, and during the trial at Huntingdon Crown Court he described his conviction for the murder of Ms Bailey as a ‘miscarriage of justice’. 

Ultimately, it was his perhaps rather careless decision to allow the donation of Diane’s brain that would ultimately lead to his conviction for his second crime. 

During the sentencing hearing, Judge Justice told Stewart: ‘You successfully passed off a murder as an epileptic fit in the circumstance I have identified playing out an elaborate, and indeed sophisticated, charade over a period of time.

‘A charade that succeeded at the time, and would have succeeded for all time but for your subsequent murder of Helen Bailey.’ 

‘It no doubt never crossed your mind that the donation of Diane’s brain for teaching and research would lead to your ultimate downfall and your conviction today for the murder of Diane Stewart.

In 2022, Stewart successfully appealed against his whole-life order reduced to life with a 35-year minimum term.