Ian Stewart has been sentenced to a whole-life jail term for murdering his wife six years before he went on to kill his new fiancée.
The 61-year-old will die behind bars after a judge handed him the UK's most severe punishment for his heinous crimes.
In 2016, Stewart killed his fiancee, 51-year-old children’s book author Helen Bailey, before dumping her body in a cesspit at the £1.5 million home they shared in Royston in Hertfordshire.
Stewart was found guilty of her murder the following year, which prompted police to look into the unexpected death of his first wife.
Diane Stewart, 47, was believed to have died suddenly as a complication of her epilepsy in 2010.
However, Stewart was yesterday found guilty of murdering her by a jury at Huntingdon Crown Court after less than two days of deliberations.
The judge, Mr Justice Simon Bryan, said the two women’s deaths occurred in “chillingly similar circumstances”.
He said Stewart "successfully passed off a murder as an epileptic fit" and that his "elaborate, and indeed sophisticated, charade" would have succeeded if it wasn't for his second murder.
Stewart has claimed in court that had returned to the Cambridgeshire home he shared with Mrs Stewart after going to the supermarket to find her collapsed in the garden.
His wife had not had an epileptic fit for 18 years and took daily medication, jurors were told, with consultant neurologist Dr Christopher Derry estimating that her risk of having a fatal epileptic seizure was about one in 100,000.
The court heard how Stewart was instructed to perform CPR on his wife, but paramedic Spencer North, who attended the scene, said there “didn’t seem to be any effective CPR”.
After police began to investigate her death, following Stewart's murder conviction in 2017, consultant neuropathologist Professor Safa Al-Sarraj was asked to examine preserved parts of Mrs Stewart’s brain.
Stewart had agreed to donate his wife's organ for scientific research.
The judge told Stewart: “It no doubt never crossed your mind that the donation of Diane’s brain for teaching and research would lead to your ultimate downfall, as it was to do, and your conviction today for the murder of Diane Stewart."
Prof Al-Sarraj said there was evidence that Mrs Stewart’s brain had suffered a lack of oxygen prior to her death, and he estimated that this happened over a period of 35 minutes to an hour.
Prosecutor Stuart Trimmer QC said her death was “most likely caused by a prolonged restriction to her breathing from an outside source”, such as smothering or a neck hold.
Ms Bailey, who was in the cesspit for three months before she was found, was believed to have died from being suffocated while sedated with drugs, his previous trial had heard.
The sentencing judge at St Albans Crown Court in 2017 said Stewart suffocated her with a pillow while she was “too drowsy to fight”, and told the court that the defendant knew he stood to gain around £1.8 million in investments plus the value of two properties after her death.
He handed Stewart a life prison sentence with a minimum term of 34 years before he could be considered for parole.
Today, Stewart looked towards his two sons who sat in the public gallery as he was led to the cells after being sentenced for his first murder.
The two boys did not make eye contact with him.
Jamie Stewart, who was taking his driving test at the time of his mother's death, had told the court that he recalled “raised voices… between my mother and father” when he was at home on study leave for A-levels the week his mother died.
The court heard that Stewart received £96,607.37 after his wife’s death, in the form of £28,500.21 from a life insurance policy and the rest from bank accounts.
The judge said he was “satisfied that the major motive for Diane’s murder was for financial gain” but had “no doubt that there were other subsidiary motives”.
He told Stewart: "I am satisfied that the seriousness of your offending is so exceptionally high that just punishment requires that you will be kept in prison for the remainder of your life.
"In the circumstances of your offending, a whole life order is not only justified, it is the just punishment for your callous and chilling murder of two separate woman who had the misfortune to be in an intimate relationship with you, and any other sentence would not exhaust the requirements of retribution and deterrence.
"I accordingly make a whole life order."
