My Lover My Killer lands on Channel 5 on Tuesday, and it's starting by telling the heartbreaking story of Sarah Wellgreen, who was murdered by her boyfriend, Ben Lacomba.
A synopsis reads: "Sarah Wellgreen and Ben Lacomba met online, and settled down, their lives becoming intertwined. Taxi driver Ben couldn't imagine an existence beyond Sarah and the children they shared so, when they separated in 2014, he continued to live in the family home.
"However, one night, he decided to commit an unspeakable act."
Beautician Sarah was found to have been murdered by her ex partner, Ben, a year after she was last seen alive.
She went missing in October 2018, but despite mass searches of 2,771 locations around where she lived, in New Ash Green, Kent, her body still hasn't been recovered to this day.
Sarah's story is a gut-wrenching one. Police eventually honed in on Lacomba - whom she split up with in 2014, but still lived with - after hearing that there were "tensions and problems" in their relationship and noticing his behaviour was odd in the wake of her disappearance.
They believed he made the cold and sinister plot to murder his ex when she tried to buy him out of the property they were living in.
After she disappeared, he inferred her mental health might have been cause for concern (something her loved ones vehemently deny).
Speaking in court, prosecutors said he acted in a "calculated manner designed to avoid detection, to leave no trace".
The convicted killer was eventually brought to justice after police from Kent poured over 15,000 hours of CCTV footage to find evidence of him driving his red Vauxhall Zafira at roughly 2am on 10th October - the time they believe Sarah's body was hidden.
He didn't return home until 4.30am in the morning, and colleagues were suspicious of his new clothes at work the next day.
Further highlighting his guilt, when he returned home his previously clean car was covered in mud, further corroborating the theory that he was out burying Sarah's body.
Paul Stimson, deputy chief prosecutor, said: "He clearly thought he wouldn't be caught on CCTV because he took a dark country lane.
"That didn't prove to be the case and it was that evidence that allowed us to say 'you lied about your whereabouts. You weren't at home in bed, you were killing Sarah Wellgreen in a rural part of Kent'.
"He knew in a short amount of time he would be left homeless and without day-to-day contact with his children and that is clearly something he couldn't live with so he made the decision to kill her."
Lacomba - who met Sarah online in 2004 - was found to have told several more lies that caught him out throughout his trial, including informing police that he didn't know where Sarah was, and alleging that a shovel there was evidence of him buying at around this time was a present from his mother.
He also threw two phones into a river and stayed silent for nine whole hours while he was being questioned.
Detective Chief Inspector Ivan Beasley, of Kent Police, said at the time: "We became suspicious of his accounts, his behaviour and then the fact that he refused to give us information and we found he disposed of his mobile phone.
"That was the trigger for me. I believed he was responsible for what happened to Sarah."
The documentary will speak to friends and family of Sarah's - including her sons - as well as those close to the case and responsible for bringing Ben to justice. On top of this, members of the Search For Sarah Wellgreen group will feature.
Search For Sarah Wellgreen was established in October 2018, and is still campaigning today, determined to recover Sarah's body to bring closure for her loved ones.
The episode sits within a wider series looking at murders which have taken place at the hands of a partner or ex partner.
The death of Kayleigh Hanks, who was killed by her violent partner Ian Paton, is another that is examined in the series, among four more harrowing true crime stories.
"Love can be a very dangerous thing," a teaser for the series reads. "These tangled tales of forbidden love, lust, jealousy and deceit, tell the tragic stories of when relationships go badly awry."
My Lover My Killer launches Tuesday 25th May at 10pm.
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