Cagefighter Paul Robson found guilty of murder, blackmail and attempted murder

Paul Robson Credit: Northumbria Police

A cagefighter has been convicted of murdering his ex-partner after he blackmailed her about an inappropriate and unlawful sexual relationship she was having with a 15-year-old boy.

Paul Robson, 50, attacked teacher Caroline Kayll, 47, and the teenager last November. Robson was also convicted of attempted murder for the attack on the boy.

Mrs Kayll did not survive the brain injuries Robson inflicted on her.

Caroline Kayll Credit: Northumbria Police

Robson also repeatedly attacked the boy with scissors and a meat cleaver, sprayed them both with ammonia and stole their phones.

Nicholas Lumley QC, prosecuting, said: "He was never going to do anything other than ruin her.

If his fury and his frustration got the better of him then he was going to take things further and end her life.

Nicholas Lumley QC

The cage fighting coach and former MMA fighter denied murder, claiming it was the boy who attacked Mrs Kayll.

Robson had a relationship with Mrs Kayll while he was behind bars in HMP Northumberland.

They lived together but split up weeks before the murder and he blackmailed her when he found out about the relationship she had started with the teenager, who cannot be identified for legal reasons.

Mr Lumley told the jury that Robson then had a hold over her, saying: "He knew things about her which she would not want to be made public."

A CCTV shot of Robson making a fuel stop on the way from Scotland to Northumberland

She was to confide in a friend that Robson was blackmailing her for £35,000 and that her ex was "going to ruin her" and tell her school, the jury heard.

Over 10 days in November, she transferred £29,000 to Robson and took out a £10,500 loan, having previously been solvent.

CCTV showed Robson "prowling" outside Kayll's house. Witnesses heard a female voice shout "get out" and later that evening Robson knocked on his former neighbour's house to say "Caroline was in a bad way", Mr Lumley said.

Robson then fled to Glasgow and remained at large while police made appeals to trace him before he was arrested.

Footage of Robson when he was arrested. Credit: Northumbria Police

He did not answer detectives' questions but in a prepared statement said he was "broken" by her death and claimed someone attacked him when he visited her home.

Jurors were told that they had seen some "very harrowing evidence" and they could be excused further jury service for 10 years.

The senior investigating officer at Northumbria Police, Detective Inspector Graeme Barr, welcomed the guilty verdicts.

He said: “This is one of the most violent offences I have investigated in my policing career and I welcome the guilty verdicts of the jury.

“Paul Robson has been fuelled by a jealous rage and attended his former address that night with one thing on his mind.

His attack on Caroline and his teenage victim was pre-meditated and demonstrated horrendous levels of violence. There is no doubt he wanted to kill or permanently disfigure both of his victims. He succeeded in killing his former partner and has left his teenage victim scarred for life.

Detective Inspector Graeme Barr, Senior Investigating Officer at Northumbria Police

Mr Justice Lavender will pass sentence at 2pm on Wednesday.