By Steve Jones & Oli Constable
BBC News
A man who killed his ex-partner and her new love interest out of “sexual jealousy” will spend the rest of his life in jail.
Marcus Osborne, 35, inflicted 99 wounds on Katie Higton and mutilated Steven Harnett’s body at the house he used to share with Ms Higton in Huddersfied.
He also raped another woman and showed the couple’s lifeless bodies to a neighbour after the May 2023 attack.
Osborne was told he would never leave prison at Leeds Crown Court on Friday.
Presiding judge Mrs Justice Lambert said the motivation for both killings was “sexual in nature”.
“Both were driven by your sexual jealousy,” she told Osborne.
“You killed Katie and Steven because you believed they had started seeing each other and their relationship was an intimate one.”
The court heard Osborne found out about 27-year-old Ms Higton’s relationship after hacking her Snapchat account.
He forced his way into the house, at Harpe Inge in Dalton, on 15 May 2023 armed with a knife and laid in wait for Ms Higton’s return from a cinema date with Mr Harnett, 25.
As soon as she stepped through the door she was brutally attacked.
Ms Higton sustained 99 injuries in the assault.
Osborne cut her face 26 times in an effort to disfigure as well as kill her, the court was told.
Prosecutor Jonathan Sandiford KC said she was “effectively defenceless, although she put up a courageous struggle”.
Osborne used Ms Higton’s phone and pretended to be her to lure Mr Harnett to the house, where he was keeping another woman captive.
He then mutilated and murdered Mr Harnett, who was left with 24 knife wounds in an attack Mr Sandiford described as “sadistic”.
The woman kept captive in the house told police that Osborne moved the bodies so they were side by side before remaining in the house for several hours.
He then raped the woman at knifepoint.
Judge Lambert said Osborne invited a neighbour in to show them the bodies, apparently “proud” of the murders, before fleeing the scene.
He later handed himself in to police.
“Your primary reason for killing them both was because Katie started a relationship with another man,” Mrs Justice Lambert told Osborne as he was sentenced.
“You were pathologically jealous of that relationship.
“I am sure you also engaged in sexual activity when Katie was either dead or dying.”
There were cries and shouts as Osborne, who had previously admitted two counts of murder, false imprisonment and rape, was taken out of the dock to begin his whole-life sentence.
Orders which prohibit a prisoner’s release are the most severe punishment available and are reserved for those who commit the most heinous crimes.
Killer nurse Lucy Letby, Thomas Mair who shot and stabbed MP Jo Cox and Damien Bendall, who killed four people including three children in Derbyshire, are others who have been told they will die in prison.
Det Supt Alan Weekes, who led the investigation, said it was “hard to understand the behaviour of anyone who acted as Osborne did”.
He added that Osborne’s “absolutely brutal offences” were among the worst he and other “experienced homicide detectives” had come across.
“His behaviour can only be described as truly monstrous.”
In a statement, Ms Higton’s family said they would “miss her laughter, her fun and jokes”.
“We will never again have the joy of loving messages from her at special times or of precious moments with her,” they added.
Four days before she was murdered, Ms Higton told West Yorkshire Police she feared Osborne would “seriously hurt or kill” her.
‘Harrowing’
Osborne had previous convictions for violent offences against two previous partners, in 2011 and 2012.
Ms Higton told police that Osborne had warned that if she got another boyfriend, “he will kill us both”.
The force said “thorough reviews of the offences are being carried out”.
Pauline Mccullagh, from the Crown Prosecution Service, said it was a “harrowing case which has left a lasting mark on our community”.
She added: “The sadistic way in which Katie and Steven Harnett were killed showed the depths of Osborne’s cruelty, and his subsequent boasts about the murders left no doubt that he felt any remorse.”Obsorne denied his victims the smallest mercies in their final moments.”
As well as his whole-life order, Osborne was sentenced to 10 years for the rape of the woman he held captive, who cannot be named for legal reasons.
He was also sentenced to 10 years for false imprisonment, with both sentences to run concurrently.