THIS is the chilling moment a double killer black widower exposed his guilt at murdering his fiancée five times to police.
Ian Stewart, 61, smothered Helen Bailey then dumped her in a cesspit of human excrement at the £1.5million home in Royston, Herte, she owned.
The master manipulator wept as he told police she had vanished after going to stay at her second home in Broadstairs, Kent.
Police later checked the cesspit and found Helen’s arm sticking out of the excrement with Stewart jailed for life in 2017.
Five years later, Stewart was convicted of murdering his first wife Diane, 47, on the back patio of the home she shared with him and their two sons in Bassingbourn, Cambs.
The deceitful monster had been able to “fool” medics into believing his wife had suffered a sudden unexplained death through epilepsy.
But in a “stroke of fortune”, Diane had donated her brain for research – with experts finding she had been either suffocated or strangled.
Documentary Faking It has now explored the two murders and how Stewart was eventually brought to justice.
It also reveals how the killer exposed his guilt at murdering Helen with tell-tale signs while being grilled by police.
Stewart can be seen sitting on a leather armchair as he told officers he couldn’t remember much from the day his fiancée vanished.
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Body language expert Dr Cliff Lansley explains: “Manipulators, disfluencies, blinking, head shake no and a single gesture from the shoulder.
“They are five indicators of deception, and we only need three. We got eight rapid blinks in a second. He’s trying to portray this calm voice, but this doesn’t fit.
“We got manipulation, increasing by playing with the glasses. We got eight disfluencies over twenty seconds, he is hesitating every two-three seconds, with a pause or an ‘ermm’, which creates thinking time.
“He’s suffering cognitive load: he is having to think too hard to answer easy questions. This is not two years ago, this is less than two weeks ago.”
For three agonising weeks, officers searched the area and checked Helen’s final movements online but there was no sign of her.
As officers arrived on his doorstep at the crack of dawn, Stewart noted “the garage door is open” before being informed he was under arrest.
Dressed just in a dressing gown, he weakly gasped “you’re joking”.
Police checked the cesspit four days later and found Helen’s arm sticking out of the excrement.
While awaiting trial, Stewart spun a ludicrous story that Helen had been kidnapped by thugs who then dumped the body at the house to frame him.
But jurors saw through his lies and in 2017 he was jailed for life after being convicted of murder.
As Stewart rotted in prison, it appeared the grisly tale had reached its ending.
That was until he was arrested and questioned on suspicion of first wife Diane’s murder in 2010.
Police had begun re-examining her death after Stewart’s conviction as her family revealed they harboured concerns about him.
Both killings bore chilling similarities – with the unwitting victims murdered at a home they shared with Stewart.
He also showed a “willingness” to cover up the killings both times and stood to inherit a small fortune from both women’s deaths.
While he was serving a minimum prison sentence of 34 years for Helen’s murder, Stewart was charged with killing Diane.
Diane’s remains had been cremated but her brain was donated to medical research and brain tissue was also kept.
Scientists were able to use this to find her chances of dying from epilepsy were more than one in 100,000.
Despite Stewart’s claims his wife was plagued by the condition, she had not suffered a seizure for 18 years and it was an “extremely low” chance her “mild” epilepsy killed her.
Even more sinister, a pathologist found the death was most likely caused by “a prolonged restriction of her breathing from an outside source”.
The oxygen to her brain had been “substantially reduced” in the hour before her collapse – leading experts to believe she had been either suffocated or strangled in a chilling echo of Helen’s killing.
In Februarie vanjaar, the fiend was handed a whole life tariff for Diane’s murder – meaning he will die behind bars.
Forensic psychologist Kerry Daynes tells the show: “Black widows can look like Ian Stewarts. And even more chilling, there may be more Stewarts out there planning their next move.”