Marcus Osborne, 35, is given a whole-life term for the murders of Katie Higton and Steven Harnett
Osborne is also given jail terms for the rape and false imprisonment of a woman on the night of the murders
At Leeds Crown Court, Osborne had admitted murdering his ex-girlfriend and her new partner on 15 May 2023
Katie, 27, and Steven, 25, suffered multiple injuries at a house in Dalton, Huddersfield
Ms Higton had suffered a "serious and sustained assault" with 99 injuries to her body, the court was told
Several knife-tip injuries suffered by Mr Harnett were intended to "torment, not to kill", the court heard
The judge, Mrs Justice Lambert, pays tribute in court to the 'dignity' of the victims' families
Marcus Osborne was "calm" during the double-murder, we hear.
Image source, GoogleAddressing Leeds Crown Court, Mr Sandiford KC says Osborne "laughed" with a "chilling" demeanour.
This is according to a woman who was in the house during the attacks but who was spared by the murderer.
The house was "a bloodbath", the court hears.
We're now hearing Snapchat messages that were exchanged between Marcus Osborne and Steve Harnett.
Mr Harnett thought he was messaging Katie Higton, who had been killed by Osborne earlier that night.
Mr Harnett was told to use a side door at the house, so he didn't see Ms Higton's body.
He was immediately stabbed by Osborne and died quickly, we hear.
One of the stab wounds went through Mr Harnett's lungs and heart, prosecution barrister Jonathan Sandiford KC says.
Osborne then went upstairs to wash his hands and change his clothes because he was covered in blood, the court hears.
The defendant said he wanted to kill Steve Harnett, with whom Katie Higton had been to the cinema, Mr Sandiford KC says.
Using Ms Higton's phone, Osborne sent a message to Mr Harnett on Snapchat, designed to lure him to the house where Ms Higton lay dead, Leeds Crown Court hears.
"Hacking with hatred" is how the attack by Osborne was described by the woman who was in the house with Ms Higton and Mr Harnett, we hear.
Katie Higton lay on the floor of her home telling Osborne: "Marcus, I can't breathe."
Both her lungs had been punctured in the attack.
It was "like a horror story, with blood pouring out of Katie", we are told.
A neighbour heard muffled raised voices at about 01:00 BST on the morning of 15 May, Leeds Crown Court hears.
That neighbour heard "male voices which sounded very angry", Mr Sandiford says.
A door was then slammed shut.
Katie Higton was then stabbed several times as Marcus Osborne said "I warned you", the court is told.
Katie Higton was "lured home to her death", the court is being told.
The woman in the house was told by Marcus Osborne to contact Ms Higton and tell her to come home, which she did.
In a police interview, we're told the woman feels guilty for contacting Ms Higton before her murder.
Ms Higton went to the Vue cinema with her new partner Steve Harnett (pictured) before they were both murdered, the court hears.
Image source, West Yorkshire PoliceOsborne was then seen on CCTV walking back from a pub to Harpe Inge.
Sometime after midnight, he then went to the house but was reminded by a woman there about the bail conditions that forbade him from being there.
Armed with a knife, he demanded to know where Ms Higton was and punched the woman inside the house.
On 12 May 2023, Marcus Osborne was arrested and interviewed on domestic violence offences, we hear.
He was released on bail with conditions not to go back to Ms Higton's home, which she previously shared with Osborne, to allow her to move back in, Mr Sandiford KC says.
The following day, Osborne was in contact with a neighbour who asked them to tell them when Ms Higton was at home.
On 14 May, the defendant was seen in the area.
He was "keeping watch" on the house and who Ms Higton was with, Mr Sandiford KC adds.
"He appeared to be agitated and looking towards [the house]", a neighbour said, according to the prosecution.
On 10 May 2023, Katie Higton made a report to police, we're now being told.
"Snapchat messages were exchanged between the defendant and Katie Higton, saying she did not want to see him following threats," Mr Sandiford KC, for the prosecution, tells Leeds Crown Court.
Ms Higton attended Huddersfield police station that same day, but no officers were available to see her, Mr Sandiford says.
In a Snapchat conversation at 13:51 BST that day, Osborne was threatening, telling her: "If I find out you're seeing someone, I'll end you fully."
An appointment was made for police officers to see her at 08:00 BST the following morning, we hear.
We are told that Osborne told Ms Higton that if she did not return to him, he would kill himself.
"The defendant said if she got a new boyfriend, he would kill them both," Mr Sandiford KC adds, referring to a statement Ms Higton made to police.
Following his previous guilty pleas, Marcus Osborne is today listening to the prosecution's case against him at Leeds Crown Court.
Over the next two days he will be sentenced.
He's in the secure dock, behind floor-to-ceiling glass, wearing a grey tracksuit.
He has arrived here from prison.
The courtroom is packed, meaning we're watching the case on a secure link in a nearby room full of journalists.
Katie Higton said it was a struggle to leave, but she was "proud of herself" for moving out, we're being told by the prosecution.
Osborne had asked her "to go back" and continue their relationship.
But when she declined, the "messages became threatening", Mr Sandiford KC says.
Katie Higton (pictured) decided to leave Osborne following an assault on 28 April 2023 - the "final straw", the prosecution says.
Image source, West Yorkshire PoliceOsborne had slapped her in the face and pushed her onto a kitchen worktop during an argument, we are being told.
He then grabbed her hair.
"The assault then continued with the defendant kicking Katie in the ribs and telling her to get out," Mr Sandiford says.
As a result, Ms Higton suffered bleeding to her ears and "significant bruising to legs arms back and ribs", with some of her injuries being filmed on a mobile phone by her.
Osborne (pictured) is a jealous man, we're being told.
Image source, Yorkshire LiveA work colleague said he would have been "battered" by the 35-year-old if he continued to give Ms Higton a lift to work.
This is all being outlined as part of the prosecution's case.
The violence, including Ms Higton being hit, came to light in 2021 when a family member noticed she had injuries.
This included bruising, according to Mr Sandiford.
"The nature of the relationship is set out in a statement made to the police," Mr Sandiford KC tells Leeds Crown Court.
Ms Higton left Osborne four days before her death and made a statement to police about his behaviour, which included how she was not allowed her own social media accounts.
"She described how the relationship, whilst it had started in a more positive fashion, had, for a period of time, become coercive, controlling and physically abusive," Mr Sandiford tells the court.
The verbal abuse was regular, the court hears, with physical violence also being used and items being thrown at Ms Higton.
We're currently hearing from Jonathan Sandiford KC, the prosecutor in the case.
He has said Osborne committed a "pre-meditated and brutal double murder", brought about by sexual jealously.
"Both murders involved sexual and sadistic conduct", he told the court.
He says a whole life order should be considered by the judge, rather than a minimum term.
This would mean Osborne would never be released.
Oli Constable
BBC News
A man is due to be sentenced at Leeds Crown Court over the next two days after he admitted murdering his ex-girlfriend and her new partner in Huddersfield last year.
Image source, GoogleMarcus Osborne, 35, stabbed Katie Higton and Steve Harnett in an attack which, according to West Yorkshire Police, lasted several hours.
They were both found fatally injured at a house in Harpe Inge, Dalton, on 15 May 2023.
At Leeds Crown Court in July, Osborne admitted murdering Ms Higton, 27, and Mr Harnett, 25.
We're reporting live on Thursday and Friday as Osborne is sentenced at the same court.