A man who was charged in murdering his ex-partner denies the allegation against him, claiming it was his ex’s 15-year-old lover who attacked him.

Paul Robson, 50, denied killing Caroline Kayll, 47, and attempting to murder the unnamed teenager at her home in Linton, Northumberland.

Robson instead alleged the boy of attacking him, despite the latter sustaining a total of 45 injuries during their altercation.

Home Office pathologist Dr. Nigel Cooper ruled that Kayll died from blunt head trauma that is similar to someone who was stamped or kicked.

The doctor added that Karyll may have suffered from strangulation as well.

Meanwhile, the boy’s 45 injuries suggest that he was stabbed, chopped, and then slashed, and there were marks on him that is consistent with someone who was bitten.

Robson underwent medical examinations after his arrest so that Dr. Cooper could identify if Robson’s story coincides with his injuries

“No they don’t. Usually the victim has injuries worse than the assailant,” the pathologist answered when asked about Robson’s injuries.

“There’s an enormous discrepancy in the number of injuries between [the boy] and Mr Robson.”

“They are consistent with Robson being the assailant and [the youth] being the victim,” Dr. Cooper continued.

The toxicology tests presented to the court show that Karyll, a former police officer, prison officer, and prison educator, previously taken cocaine prior to the encounter but the pathologist said she was not under the influence at that time.

Prosecutors argued that Robson had been blackmailing his ex-partner and received £29,000 ($40,000) from her, as she feared he could “ruin her.”

Robson and Karyll met when the former was behind bars at HMP Northumberland where she worked before becoming a school teacher.