The lead detective in the case of murderous fiancée Julie Dixon, who lied about locking her partner in a cupboard and burning him, initially thought she was a victim too.
Senior investigating officer Stuart Gibbon added that it was one of the most challenging cases of his 30-year career as the killer fooled police for months.
Dixon murdered her partner of 15 years, David Twigg, 46, in his workshop after locking him in a cupboard and setting the building on fire at Burgh le Marsh near Skegness, Lincolnshire, on March 13, 2011.
The then 43-year-old delivers 'a performance worthy of an Oscar' during the 999 call, where she spoke hysterically about masked intruders.
Now the case is the subject of a new Channel 5 documentary A Killer Makes a Call, which details how she blamed the murder on two masked intruders, but when police found no evidence of a raid they arrested her instead of them.
Lead detective Stuart Gibbon believed killer Julie Dixon (pictured) was a victim before finding evidence that resulted in the arrest of the then 43-year-old
Dixon murdered her partner of 15 years, David Twigg (pictured with Dixon), 46, in his workshop after she locked him in a cupboard and set fire to the building in Burgh le Marsh, near Skegness, Lincolnshire, on March 13, 2011.
Mr Gibbon (pictured) said in 2018: 'She had injuries consistent with a fire. She had soot on her face and her hair was singed, making her look like the victim.”
Mr Gibbon, who left the force in 2018, acknowledged that police were challenged early on by a case the likes of which Burgh le Marsh had never seen before: a murder involving two unknown alleged intruders and only one witness.
“She was quite rightly treated as a victim,” he said Lincolnshire Live in 2018.
“She had injuries consistent with a fire. She had soot on her face and her hair was singed, making her look like the victim.”
But the police were unaware of the reality that their witness was not telling the whole truth.
“A lot of time and effort has gone into trying to get information from Julie. She was desperate and there wasn't much to tell from her description of the intruders. It turns out they were never there and didn't exist.'
Lacking information about the mysterious suspects, Dixon was arrested on June 6, 2011 to be questioned as a suspect for the first time.
Even then, according to Mr Gibbon, it took time to crack the killer because the fire destroyed a lot of potential evidence.
The detective delved into the finances of Mr Twigg's company and discovered that the 48-year-old was on the verge of bankruptcy – but the furniture maker knew nothing about it as all discussions about the finances were conducted by his fiancée.
Mr Gibbon suspected that Dixon tried to hide the financial ruin from her partner until it got to a point where she could no longer continue.
All the while, Dixon claimed she had forgotten her passcode for a mobile phone obtained by Lincolnshire Police.
It also emerged that she had bought petrol the morning of the fire, although she claimed it was for the lawn mower.
In a prepared statement, Dixon changed her story to say she and Mr. Twigg had a suicide pact.
Whatever the case, it confirmed there were no intruders. The focus was on finding out if the victim was suicidal.
No evidence was found to indicate Mr Twigg was considering taking his own life, nor were the earlier interviews with Dixon. Investigators asked if there was enough evidence to prosecute their new suspect.
During the court proceedings, Dixon's story changed again, claiming Mr Twigg's death was assisted suicide.
It turned out she had been looking for ways to kill someone without it showing up in an autopsy, and ways to hide tablets in food before her partner died.
Mr Gibbon recalled that the killer 'showed no remorse whatsoever' during the trial.
The judge presiding over the case at Lincoln Crown Court said Julie's “performance” during the 999 call, to emergency services at the scene and later at hospital “would be worthy of the highest praise had she been an actress in a fictional drama and would have deserved an Oscar'.
The then 43-year-old was sentenced to 23 years behind bars after ultimately pleading guilty on the second day of her trial.
Addressing Dixon directly, Judge Michael Heath told her: “David Twigg was an amiable, hard-working and honorable man. What you did to him was bad.”
Addressing Dixon directly, Judge Michael Heath told her: “David Twigg was an amiable, hard-working and honorable man. What you did to him was bad. There was a significant degree of planning and premeditation.
“One can only imagine the pain your prolonged and frequent lying has caused David Twigg's parents.”
The court heard the couple had an outwardly happy relationship, but Julie managed to hide the chaotic financial state that had engulfed David's business.
David's best friend Keith said: 'The way David died will haunt me for the rest of my life. I was absolutely devastated, no one deserves to die like that. He was my best friend. It still bothers me to this day, and it will continue to do so until I die.”
A Killer Makes a Call airs on Tuesday, May 21 at 10 p.m Channel 5