The brutal murder of Spalding dinnerlady Elizabeth Edwards and her daughter Katie at the hands of her other daughter last April shocked the nation
The police described the killers of the brutal double murder of Spalding dinnerlady Elizabeth Edwards and her teenage daughter Katie as the "UK's youngest double murderers".
But the country was shaken earlier this month when their identities were revealed by the news that the killers were none other than Elizabeth's other daughter, Kim, and her boyfriend Lucas Markham.
A documentary about the killings is set to air tonight, and will play a recording of Lucas' emotionless police confession, never before heard by the public.
The audio recording, which will be played on Murdered By My Daughter tonight, shows the then-14-year-old calmly describing how he killed both of the victims: "I went into her mum's room and stabbed her in the neck while she was asleep and smothered her face with a pillow.
"After I knew she had gone, I went into Katie's room and I thought I stabbed her, but I'm not a hundred per cent sure if it was her or the mattress and then I smothered her face with a pillow too."
Elizabeth's partner, Graham Green, has been interviewed for the Channel documentary, and described Kim as the next Myra Hindley - the girlfriend and accomplice of Moors Murderer Ian Brady.
He said: "I think she's another Myra Hindley as far as I'm concerned. She should never, never, never be let out.
"She's trying to put herself on the map. How would you go about planning to kill your mother and sister? How can you plan that?"
The leading officer of the investigation, Det Supt Martin Holvey was shocked by Markham's lack of remorse: "You recount the story to your team and everyone sits there, hardened detectives, and thinks, 'I can't believe what you're hearing'.
"Over 30 years as a cop, you look at this case and there's nothing that rivals it. A really brutal, chilling, cold and callous act that was carried out by these two children on two defenceless victims."
The two murderers plotted to kill Elizabeth and Katie because her mother had tried to split the couple up, as Lucas was a known thug in their local area - and they killed Katie for receiving more attention than her from their mum.
After murdering their victims, the two had sex and watched the Twilight films whilst the bodies lay upstairs.
When is Murdered By My Daughter on TV?
Murdered By My Daughter, the TV documentary about the murder of Elizabeth Edwards and her daughter Katie at the hands of her other daughter Kim and her boyfriend Lucas Markham, will air tonight on Channel 5 at 9pm.
[ebed:http://players.brightcove.net/791646182001/default_default/index.html?videoId=5483405138001]
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