A domestic abuser has been given a whole life order for murdering his ex-partner and her new boyfriend in a “ferocious and merciless” knife attack.

Marcus Osborne said: “Romeo and Juliet can die together now” after the brutal double killing which left Katie Higton, 27, with 99 injuries and Steven Harnett, 25, with 24 wounds including mutilated genitals.

Leeds Crown Court heard Osborne, 35, lay in wait for Ms Higton and launched a brutal attack on her as soon as she came through the door of the house they once shared in Huddersfield, West Yorkshire.

Osborne then used Ms Higton’s phone to pretend to be her and lure Mr Harnett, 25, to the house.

He then raped another woman, who he had held captive in the house overnight, at knifepoint.

The court heard four children were in the house during the murders, which happened in the early hours of May 15 last year.

Prosecutor Jonathan Sandiford KC said: “The defendant committed a premeditated and brutal double murder motivated by sexual jealousy, a desire to exercise control over Katie Higton, an unwillingness to accept her decision to leave him and her freedom to form a relationship with another man.”

Ms Higton had been in a relationship with Osborne for five years, but left him in early May last year after an assault on April 28 which was “the last straw”.

She later told police the relationship had become “coercive, controlling and physically abusive” in the last two years and that she had been regularly assaulted, including one incident when he threw a cat at her, the court heard.

Osborne also has convictions for violent offences against two previous partners in 2011 and 2012, Mr Sandiford said.

In the days before the murders, Ms Higton told West Yorkshire Police Osborne had told her “he would slit her throat if she said what he had done”, and that “if she ever got a boyfriend he would kill them both”.

On May 12, Osborne was arrested on suspicion of domestic violence offences and bailed with conditions not to go back to their home, but spied on her over the following days before taking a taxi to the house on the night of the murders.

The court heard he found out about the developing relationship between Ms Higton and Mr Harnett by hacking into her Snapchat account.

A victim personal statement by Ms Higton’s mother Nicola McAlister, read in court, said Osborne was “a monster of the worst kind”.

The judge, Mrs Justice Lambert, said Ms Higton’s murder was a “merciless and sustained attack on a woman who was completely defenceless”.

She said that during the attack, which started “before (Ms Higton) even got through the front door”, Osborne was heard saying: “I warned you I was going to kill you… this is your fault this is happening.”

The judge said the woman who was held captive in the house described Osborne washing himself between killings, laughing and jeering, later even inviting a neighbour into the living room to see the bodies “as if you were proud of what you had done”.

She imposed 10-year concurrent sentences for the rape and false imprisonment of the other woman in the house.

The judge told Osborne: “There are no mitigating factors in your case other than your guilty plea. There is no psychiatric or other evidence placed before me to explain or help me understand your actions.

“This is a case of such exceptional seriousness that even a very long minimum term would not be a just punishment. What you did that night was horrific.”

A family member shouted “I hope you rot in hell” from the public gallery as Osborne was taken away.

The judge said the killings were “sexual in nature” and driven by Osborne’s “pathological jealousy”.

She told Osborne: “They were driven by your sexual jealousy arising from Katie’s decision to start a new relationship with Steven.

“I do not accept (the murders) are explained by your entrenched insecurity about being abandoned as a result of a neglected childhood.

“Everything you did was motivated by sex and your need to sexually humiliate and degrade.”