Despite their seven-year age gap, sisters Sabah and Saima Khan were so close their neighbours thought they were twins.
The siblings were inseparable and would do everything together from shopping trips to picking up Saima's children from school.
They even lived together, all squeezing under the same roof of their parents neat and tidy semi-detached in Challney, Luton.
But secretly, Sabah, then 27, hated her sister for having something she longed for – a relationship with her husband, Hafeez Rehman.
Sabah had embarked on a sordid four-year affair with taxi-driver Hafeez, and the pair would sneak off for sex in his car and in the family home while Saima, 34, was off at work.
When Hafeez eventually tried to break off the relationship, Sabah hatched a twisted plan to kill her older sister and take him back for herself.
She paid £5,000 to a witch doctor in Pakistan to curse her sibling but when that half-baked plot failed she decided to carry out the execution herself.
She lured Saima home early from work one night and launched at her with a kitchen knife as she stepped foot in the hallway.
Sabah stabbed her victim 68 times and with such ferocity she almost decapitated her.
When Saima's four sleeping children were awoken by the noise, one of them shouted down from their bedrooms to Sabah, 'Are you killing a mouse, aunty?'
She span a web of lies when the police arrived and claimed her sister had been brutally murdered in a home break-in gone wrong.
But detectives and a jury saw through her deceit, and she was jailed for life for the horrifying killing.
Saima and Sabah’s parents still live in the same house but understandably refuse to talk about the trauma of their daughter’s murder ten years on.
But what became of the man at the heart of the deadly love triangle?
Shockwaves ripped through the community of Challney, Luton, when ordinary mother-of-four Saima Khan (pictured) was murdered in the hallway of her home
To her family's horror, Saima (right) was murdered by none other than her beloved younger sister Sabah Khan (left)
At the centre of the warped love triangle which ripped apart the two sisters was Saima's husband Hafeez Rehman. He partook in a four-year secret affair with his sister-in-law, having sex with her in his taxi and in the Khan family home while Saima would be at work
Saima's husband and parents had been attending a late night funeral on May 23, 2016, and returned home at 11.30pm to see her body lying in a pool of blood. Police initially suspected Saima was killed in a botched burglary
Despite painting the picture of a grieving husband in court and in tributes after his wife's death, Hafeez wasted no time in moving on, the Daily Mail can reveal.
He travelled back to his native village of Gulpur, in Pakistan-administered Kashmir, and got married to a second wife in a small, intimate ceremony, before bringing her back to Luton where they have since had two children together.
A source told the Mail that he was shunned by his extended family in Gulpur for his infidelity, but is still seen frequently dropping off his and Saima's children to their grandparents home - the same house their mother was killed in.
He never dares to enter the home himself, instead parking up the street to pick up and drop off his children.
The family friend said: 'He's not really liked in the family anymore after what happened.
'You see, they [Hafeez and Saima] are both from the same family so it caused a lot of problems.
'His extended family have kind of distanced themselves from him.'
But while Hafeez could enjoy a fresh start with his new family, the Khan's were forced to pick up the pieces of a crime so horrifying that it sent shockwaves around her community that are still felt to this day - a decade on.
On May 23, 2016, Saima and Sabah's parents, along with Hafeez, returned home from an evening funeral service to scenes from a horror film.
Their eldest daughter Saima was lying dead in a pool of blood in their corridor, her head nearly decapitated. Their younger daughter Sabah was unhurt but covered in her sister's blood.
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Police were called and Sabah claimed her sister had been stabbed to death in a botched burglary.
She had been in the shower, she claimed, and came out to see her beloved sister lifeless in the hallway.
At first no one had any reason to doubt her story.
It was unforeseeable that Sabah could ever hurt a hair on Saima's head.
One family friend who lives on the same road said: 'It was about 11.30pm. I woke up because I heard screaming outside and it was their mum.
'When we went outside the paramedics were already there. You could see Saima's body there in the corridor.
'Sabah actually asked me to go into the house and go upstairs to make sure the children are okay.
'They were so close, so Sabah being involved was the last thing I could think of.
'She was very calm [on the night], as if nothing had happened.'
They added: 'She seemed perfectly fine, the way she was in her senses and everything. It was not a normal way for somebody to react.'
The truth was too horrifying to contemplate. Sabah had stabbed her sister with a kitchen knife she had bought from Tesco just a day before.
She then changed out of her bloodstained clothes, stuffed them in a bin liner along with the murder weapon, and hid them under cardboard boxes in her room.
Days later, detectives recovered the evidence during a search of the house.
Pictured: The murder weapon used by Sabah to stab her sister 68 times
CCTV footage revealed Sabah buying the knife from a Tesco store before killing her defenceless sister
Sabah was charged with her sister's murder and the seedy details of the affair finally came to light.
A court heard how Hafeez had got his sister-in-law pregnant because he refused to use contraception and Sabah was forced to have an abortion rather than expose their relationship.
Hafeez had no plans to leave his wife for his mistress but Sabah became infatuated and wanted him 'entirely for herself'.
In an effort to distance himself from her, the taxi-driver planned to move out of the Khan family home with Saima and their children.
But family sources suggested that Saima, who was unaware that her husband was sleeping with her sister, did not wish to move from her family, and an annex had initially been built in the garden for them to live in.
Sabah saw no other option but to take her sister out of the picture – and began to plan the murder that would destroy her family and see her jailed for life.
Bitter text messages to Hafeez showed Sabah calling her sister a 'b***h' and in one message she promise to rip her 'heart out' and show him what he means to her.
Sabah also began searching the internet for 'poisonous snakes', 'how to hire a killer' and '16 steps to kill someone and not get caught'.
She eventually contacted a 'fixer' in Pakistan to use black magic to kill Saima - paying £5,000 to a witch doctor to 'finish off' her sister.
She would message the fixer in the third person, writing: 'Sorry to bother you again and again.
'My friend is really upset now Hefeez does not even look at her... he says he realises his mistake... You finish off Saima as quick as possible so Sabah can get her Hefeez back.'
After this failed, she decided to take matters into her own crazed hands.
Sabah purchased a knife the day before, and at around 11pm on May 23, 2016, lured Saima home by messaging her that her children were crying.
As Saima entered, the lights were switched off for eight minutes, during which time she was knifed to death in a savage frenzy.
Sabah had tried to stage the scene to look like a burglary, smashing the window, and concealing the murder weapon and her bloodstained clothes in bin liners.
She told officers she found Saima lying dead in a burglary gone-wrong and officers initially believed her until they found the murder weapon in her room.
In police bodycam footage played at her trial Sabah could be seen on video explaining how she had tried to stop the bleeding by covering Saima's wounds.
When asked by an officer why she had blood on her hand, she claimed to have wounded herself on 'glass' which was shattered on the floor after the 'break-in'.
A family source said no one ever considered that Sabah could have killed her sister because they were so close.
They told the Mail: 'The two sisters, you would never see them apart. It was them two together all the time.
The Crime Desk can reveal that Hafeez returned to his native village in Pakistan-administered Kashmir and remarried, before returning to Luton with his new wife
Before police arrived at the murder scene, Sabah had attempted to stage a burglary by smashing a window before calling police and claiming her sister had been murdered by an intruder when she was in the shower
Detectives initially investigated Sabah's burglary claims before arresting her eight days later when they found the knife in a bin bag in her bedroom (pictured)
'Every time we saw them they seemed like twins, even though they were a few years apart. They were that close.
'Whether they were picking up Saima's children from school, or going shopping, they would always go together.
'I couldn't believe the affair. I think what happened is that Sabah got very obsessed with him. She was more interested in him, while he was just passing time.'
During the trial, Hafeez had tried to downplay his role in the affair, claiming that he had been forced to have sex with her for four years.
But Jo Sidhu QC, Sabah's defence barrister had revealed how during the affair Hafeez had 'begun exploring his options', even inquiring as to whether it was permissible in Islam to marry his sister-in-law.
While he said he had tried to break it off, Sidhu argued their relationship had remained sexual until days before the murder and Hafeez had even warned off a suitor who had started to develop a relationship with Sabah.
During her murder trial, it was heard in court that Sabah was a 'lonely individual, had traits of mental health issues and had in the past cut and strangled herself'.
While her defence argued that the 'remorse will infect her for the rest of her days', she showed no emotion as she was jailed for life with a minimum of 22 years.
She had appealed to have her sentence reduced in 2017 but failed as judges ruled the sentencing for the 'horrendous and brutal murder' was not 'manifestly excessive'.