A man, Paul Robson, aged 50, reportedly drove 150 miles from Glasgow to Nothumberland to murder his ex-lover when he discovered she was having sex with a 15 year old teenager.

Paul Robson,  a trained cage fighter subjected teacher Caroline Kayll, 47, and the teenage boy to a horrific assault according to prosecutors but he denies the charges.

Man stabs his ex girlfriend to death after he discovered she was having s3x with 15 year old boy

According to prosecutors, Robson armed himself with two bottles of ammonia, then stabbed and slashed his former girlfriend and her teenage lover with a kitchen knife, scissors and a meat cleaver and then squirted them with the liquid.

He also allegedly bit the lad and stamped on Caroline’s head and neck before cutting off chunks of her blonde hair, prosecutors say.

After the crime, he allegedly fled with their phones so they were unable to call for help.

The victim’s family and friends later told police they saw that her Facebook account had been changed in the hours after the attack to say she was in a relationship with a 15-year-old.

Man stabs his ex girlfriend to death after he discovered she was having s3x with 15 year old boy

Screenshots of her intimate phone chats with the boy were also posted on Facebook with one chat showing her telling the teenager “Having naughty thoughts about you.”

Prosecutors also say Robson, a former convict, previously demanded £35,000 from Caroline and threatened to “ruin her” if she didn’t pay up.

She gave him thousands of pounds and even took out a £10,000 loan to satisfy his demands – but former convict Robson was still set on violent revenge, the jury was told.

Prosecutor Nicholas Lumley QC said: “The defendant was a well built and powerful man. He decided he was going to confront Caroline that night.

“Before he did so he went to Homebase and bought two bottles of ammonia, a pack of screwdrivers, a pair of pliers and adjustable wrench.

“Those items and a locksmith device he bought shows he was prepared to use force to enter her home and he planned to use the ammonia as well.

“Caroline and the boy were attacked and viciously so.

“As he left her for dead he paused to take her phone and also took the boy’s phone leaving them with no means of calling for help – the actions of a vindictive man.”

Caroline met Robson while working as a prison officer at HMP Northumberland where he was serving a sentence and where her ex husband Ian Kayll was a prison manager.

She separated from her husband in 2018 after getting involved with Robson, Newcastle crown court heard.

He was released from prison in the autumn of 2018 and a year later moved in with Caroline at her home in Linton, Northumberland.

But in the autumn of 2020 they separated.

Robson then discovered that Caroline, now a teacher, had begun a relationship with the teenager.

Mr Lumley said: “She was in her mid to late 40s and he was 15. That may be an affront to the morals of many and it is against the law but of even greater significance is that the defendant somehow found out about it and did not take it very well.

“So he, in addition to having a reason to be angry at her, also had a hold over her.”

Robson began sending her threatening texts demanding money, it was said.

Mr Lumley said: “He is starting to lose his rag.

“She told a friend that he was being nasty and he was blackmailing her. She mentioned £35,000.

“It’s obvious that he was applying direct pressure, threatening her, telling her that he would make her pay, that he would make public her relationship with the boy with all the personal and professional consequences that would have.”

On November 15, 2020 that was when Robson drove to Caroline’s house to allegedly carry out the heinous attack

The teenage boy told police how Robson didn’t say a word as he carried out the assault.

He said: “He gets scissors and comes into the room and he was on my back, not saying anything.

“I said: ‘Whoah, what’s it about?’ but he was on my back, he’s canny heavy, he took hold of my shoulders and stabbed me. He’s holding me with one hand, stabbing me with the other.

“I was fighting with him, I was saying ‘whoah’. He gets up and says: ‘Don’t move or I’ll kill you’ and he came back with bigger blade, a 7in blade, I have seen it in the kitchen drawer.

“He stabbed me in the back and stabbed me a few times in the struggle.”

The teen said he suffered a deep cut to his left hand as he tried to prevent Robson stabbing him further.

He went on: “He said come down and we went down and she’s [Caroline] on the floor at the back door.

“I went in the kitchen because I was covered in blood. I went straight to the tap and he cuts her hair off. He was cutting her hair with scissors. She wasn’t responding. He came into the kitchen and gets a cleaver from the kitchen drawer and he hits me in the head twice with the cleaver. I was dizzy, I couldn’t really stand up.

“He got a garden hose and sprayed her in the face.”

Mr Lumley added: “She was in a critical condition. She had many facial and head injuries and a cut across both buttocks. Her heart had stopped.

“The boy was bloodied, bewildered and bore terrible injuries.”

They were both rushed to hospital but doctors were unable to save Caroline, although she was kept alive on a life support machine for 36 hours.

Robson was arrested in Glasgow the day after her life support machine was turned off.

Man stabs his ex girlfriend to death after he discovered she was having s3x with 15 year old boy

He refused to answer police questions and claims he was the victim of an attack.

He said: “I am emotionally spent. I never intended to kill anyone. I can’t believe Caroline is dead, I can’t believe she is gone.

“The whole thing is like a nightmare, like a bad dream.

“I recall going to Caroline’s house, I recall she let me in through the back door after I knocked.

“We were arguing and then I was hit from behind on my head and back and I fell forward. I recall something around my throat, I was feeling all sorts of emotions.

“I felt dazed and was feeling sick and scared and I felt like everything was unravelling. I remember trying to ask for help. Ifeel broken.” He said