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The 65-year-old mum-of-two from Surrey was handed a life sentence after she bludgeoned her husband Richard Challen, 61, to death with a hammer in August 2010 following decades of being controlled and humiliated by him.
But, in a first for the courts, she later had this sentence reduced to four years following a high-profile appeal, in which she cited Richard's "coercive control" as a defence.
Here she is talking about her crimes:
Now, a new BBC documentary made by filmmakers Rowan Deacon and Lizzie Kempton, speaks to Sally herself as well as the couple's closest family and friends - most of whom have not spoken publicly before - in order to shine further light on the complex case.
The programme also follows both legal teams in the lead-up to the groundbreaking appeal, and offers a rare insight into a case which has shaped criminal justice to this day.
The harrowing documentary starts right at the beginning - and it's clear to see why, at first, Sally was handed a murder conviction.
In Sally's gut-wrenching first police interview, she tells detectives that she was consumed by jealously and fears over his infidelity, and explains: "I just can't take it any more. I can't take the not really knowing if I've been spun a line or anything.
"The hammer's there and I just pick it up and I use it. I don't know why. I feel if I can't have him nobody else can. I don't want anybody else to have him if I can't."
Damningly, she later told police she'd picked up the hammer from her new house and taken it with her to meet Richard in her handbag.
Meanwhile, in reflective interviews, even her own bother Chris admits he questioned whether her "vacant" expression in court was a sign of guilt, as her other brother Terence described her vague answers when on the stand as "pretty unsavoury".
But as the footage delves further into the complex case, it becomes clear there was a lot more going on under the surface.
As Sally was handed her life sentence, her family and friends questioned: "Why didn't the court look at Richard's behaviour?"
The answer at the time appeared to be: "You shouldn't speak ill of the dead".
But the statements Sally had given her lawyer Harriet Wistrich - co-founder of Justice for Women - and the stories she'd told to those close to her, revealed that it was crucial to do just that.
They told how Richard was unfaithful and called Sally 'crazy' when she pulled him up on it.
He controlled little things like what colour clothing Sally wore, how much of her salary she was allowed and how often she spoke. He told her to take her favourite necklace off "because she didn't deserve it," and would call her nasty names, like "sl*t" in bouts of anger.
Plus, it wasn't just mental abuse. Sally also alleges anally raped her on more than one occasion, and forced her into sex when she didn't want it.
"I just let him do it, but it would have been clear that I didn't want it," Sally said. "Occasionally I tried to get out of sex by saying I had a headache, but he would proceed anyway. He told me to go upstairs and get ready, which meant being cleaned and washed, and sometimes he would leave me waiting for ages".
When she eventually plucked up the courage to leave him, it was only short lived.
And when they got back together, Richard went as far as to write a list of conditions Sally had to abide by if she wanted to get back together, banning her from smoking and even interrupting him, and threatening to take the majority of their assets away should she ever leave him again.
While he reveals he wasn't aware of the full extent of his father's controlling character, even Sally's son David concedes he knew all too well that he was "one of those characters you don't really want to get on the bad side of."
"I had discovered the extent of the abuse after he died. I didn't acknowledge it as abuse because I didn't realise that's what it was," he says. "But I do know the way he treated her was horrible."
Thankfully, we now know Sally's appeal was successful, and she was released with no retrial. But the documentary also shows what a tough road it was to get to that point.
Less than 10 per cent of applications for appeal against conviction are successful, and as the court footage showed, proving that coercive control counted as a partial defence was incredibly difficult considering it had never been done before, and only one half of the marriage was alive to tell the story.
Ultimately, Wistrich used numerous witness statements taken from 2010, emails from Richard to Sally, and months of prison visits and video calls with Sally in order to prove her case.
Speaking at a press conference after her release, Sally said: "Many other women who are victims of abuse as I was are in prison today serving life sentences. They should not be serving sentences for murder but for manslaughter."
She added: "I still love Richard and miss him dreadfully and wish that none of this had happened. I'm just so happy I can begin to live my life again."
Her son David said there were "no words," when asked how it felt to have his mother free.
You can follow Sally and her family's journey to justice from beginning to end when the documentary airs next Monday on BBC Two at 9pm. It's sure to be a chilling watch.
Featured Image Credit: BBC/Minnow Films/Challen Family
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