Ian Stewart: The 'master manipulator' who murdered wife Diane and fiancee Helen Bailey

A "master manipulator" - and now a convicted double murderer.

Ian Stewart thought he could outwit justice - but it was his narcissism and belief in his own ability to lie and control others that ultimately led to his downfall.

Having escaped the attentions of police for more than six years after the death of his wife Diane Stewart, it was the murder of his partner Helen Bailey in 2016 that shone a spotlight on the similarities between the two cases.

It prompted a six-year investigation - and a three-and-a-half week trial - which has now led to the father-of-two being convicted of murder for a second time.

Stewart, 61 - who was already serving a life-sentence for killing Ms Bailey - was found guilty by unanimous verdict at Huntingdon Crown Court.

Det Supt Jerome Kent, from Cambridgeshire Police, led the investigation into Mrs Stewart's death.

"Ian Stewart is a master manipulator," he said. "He is able to control people, he is able to tell lies to create a narrative around those lies, and then maintain those lies over days, weeks and - in this case - years to cover up what he's done."

Who is Ian Stewart?

Described by police as an "intelligent man", Ian Stewart is a retired software engineer. He met Diane Stewart when they were both students at Salford University during the 1980s.

The pair were married in 1986 and moved to Bassingbourn in Cambridgeshire in the 1990s. They had two sons - Jamie and Oliver - and all four were members of the local bowls club.

Neighbour Paul Easton told ITV News Anglia: "I found it a little bit difficult making conversation with Ian. He tended to stare over your head or to the left rather than looking at you."

But, as other witnesses also reported during Stewart's trial, Mr Easton said the couple appeared happily married.

"Together they seemed fine, as far as we saw them. But I think it's different seeing them as a neighbour rather than what might be going on inside four walls."

While Mrs Stewart, who was 47 when she died, worked as a school secretary, her husband retired due to ill health and relied on his wife for care and support.

It was a role children's author Helen Bailey took on when the pair began their relationship - having met through a forum for widowed partners.

"I think he is a narcissist," said Det Supt Kent. "It's all about him. About what he wants and he controls people around his frailty and around his medical needs."

The couple moved to Royston in Hertfordshire in 2013, living in a £1.5m home with Stewart's sons.

It is believed they had assets worth more than £4m.

Murder of Helen Bailey

Helen Bailey was reported missing from her home in Royston by Stewart, after last being seen out walking her dog in April 2016.

Stewart claimed he had found a note from her saying she needed space and was going to stay at the family home in Kent - but four days later became concerned enough to call police.

It prompted a three-month search during which Stewart feigned distress and concern - an act he maintained even when police arrived at the house to arrest him.

Ms Bailey's body was found dumped in a cesspit hidden away in the garage, alongside her pet dog Boris.

A murder trial heard Stewart had spent four weeks secretly drugging her so that when he finally tried to kill her, she would not be able to fight back. Pathologists found that the cause of death was most likely suffocation.

Stewart was convicted of her murder in 2017 and sentenced to life imprisonment with a minimum term of 34 years.

Murder of Diane Stewart

On the day Stewart began his prison sentence, police announced their plan to reinvestigate the death of his first wife, Diane Stewart.

The 47-year-old had died suddenly in the garden of their Bassingbourn home in June 2010.

Stewart claimed to have been at Tesco at the time and came home to find her collapsed on the ground.

In a 999 call, played to jurors during his trial, he can be heard suggesting his wife had had an epileptic seizure.

That was the conclusion an inquest came to - with her official cause of death recorded as sudden death in epilepsy (SUDEP).

Twelve years later, and following a six-year investigation, that version of events has been turned on its head.

Det Supt Kent points out it was Stewart who first suggested epilepsy as the case of his wife's death - the first sign of him creating a narrative that he would maintain for many years.

"If there isn't anything obvious to alert police and paramedics to the cause of death, we are very reliant on the medical history provided to us by immediate family and friends," he said.

"It's Ian Stewart that's created this false narrative - the narrative he created and planned. "

The Crown Prosecution Service (CPS) said Ian Stewart made the decision to have his wife cremated "to ensure no further examination of her body could take place".

But Mrs Stewart had already agreed to donate her organs - including her brain - to medical research.

"Ian Stewart had no option but to consent... though coroner's office records show that he requested nobody be informed of this," a CPS spokesman said.

Brain tissue was re-examined as part of the police investigation and prosecutors told the jury "the cause of death was most likely caused by a prolonged restriction of her breathing from an outside source" - calling into question Stewart's long-maintained version of events.

A sense of deja vu"You're joking" - when Ian Stewart was told he was being arrested on suspicion of murdering Helen Bailey, those were his very first words as he stood at the bottom of the stairs at their £1.5m home.

Two years later, he was sitting in a police car having been taken from his prison cell to be told by police he was also suspected of murdering Diane Stewart.

"You're joking," he said again.

For police, it was just one more "striking similarity" between the two cases.

"The main one is that he's in an intimate relationship with both of those women," said Det Supt Kent. "He lives with both of those women. He's the creator of the narrative of what happened which resulted in the deaths of both of those women."

In the case of Diane Stewart, that meant introducing the idea of an epileptic seizure at the very start of his 999 call. After he had killed Helen Bailey, Stewart was the first person to describe her as a missing person.

Both murders took place when no one else was at home - and Stewart could feel confident they would not return unexpectedly.

The killer claimed he had also been out when both women died.

It was those many striking similarities that led police to reinvestigate Mrs Stewart's murder - and brought Stewart's 12-year escape from justice to an end.