Ross McCullum admits strangling Megan Newborough and then cutting her throat but denies murder (Picture: PA)

A lab worker who killed a co-worker in a ‘blind rage’ has denied murdering her after feeling ‘humiliated’ by his own sexual impotence.

Ross McCullum throttled 23-year-old HR worker Megan Newborough then cut her throat after inviting her to his home in Leicestershire on August 6 last year.

He says he was triggered by memories of claimed sexual abuse during oral sex. But John Cammegh KC, prosecuting, called his account a ‘pack of lies’.

Jurors have heard the pair had a brief consensual ‘sexual encounter’ in woodland the weekend before Ms Newborough’s death. Afterwards, McCullum ordered Tadalafil pills, used to treat erectile dysfunction, off the internet.

Once they were delivered, he invited her to his home, with Mr Cammegh saying text messages between them showed he was ‘extraordinarily excited’ about the visit.

The prosecutor challenged McCullum, who admits strangling Ms Newborough and then cutting her throat but denies murder, with what he suggested was the real reason for launching his ‘attack’.

Mr Cammegh said: ‘I suggest you attacked her in a blind rage, because you’d been humiliated.

‘Your penis didn’t work. You hated her for all the things she was and all the things you couldn’t be.’

Ross McCullum is on trial at Leicester Crown Court

McCullum has admitted the manslaughter of Ms Newborough (Picture: PA)

McCullum replied: ‘When we were out having a walk (the weekend before) at the wood, did I feel humiliation, did I strangle her there? No.

‘I’d never do something that awful (just) because I was humiliated,’ he added.

Mr Cammegh then asked: ‘When you had your hands around her neck, did it turn you on, as you strangled her to death?’

‘No,’ McCullum replied.

Turning to McCullum’s use of the knife, Mr Cammegh asked: ‘You were trying to take her head off weren’t you, you were trying to dismember her body?’

McCullum replied: ‘No, I didn’t want to cut her head off.’

Mr Cammegh suggested McCullum had got an old motorcycle helmet from his garage at home, where he lived his parents, ‘in order to transfer her head out of your house?’

McCullum replied: ‘The helmet was there because I wanted my dad to see it, see whether it was worth any money.’

Court artist drawing of McCullum during his trial at Leicester Crown Court (Picture: PA)

Turning to events immediately after killing Ms Newborough, McCullum denied Mr Cammegh’s assertion, when he asked: ‘You, I suggest, show remarkable coolness and precision of mind in the decisions and choices you now make?’

McCullum accepted getting sheets and ‘fancy dress clothes’ to mop up blood, collecting a change of clothes he ‘grabbed off the end of the bannister’, and then placing Ms Newborough in her own car, and driving from his house.

Before dumping Ms Newborough’s body in a lane near Woodhouse Eaves, Leicestershire, McCullum also said he ‘chucked (her) phone out the window’.

CCTV footage then showed McCullum parking the Citroen at Loughborough College campus, changing clothes – as he can be seen looking around – and dumping items in a nearby skip.

Mr Cammegh said: ‘Notice the methodical, careful way you change your clothes.’

When McCullum got home, having got a taxi to drop him at the end of his road he accepted sending Ms Newborough’s phone a text which read: ‘Did you get back okay, baby?’

Later that night, around 11.30pm, McCullum also accepted leaving Ms Newborough a voicemail, also played to court, which said: ‘You haven’t rang back, or text me or anything.

‘It’s probably nothing, probably you fell asleep – I had a fun time earlier.’

‘Quite a performance,’ said Mr Cammegh, who then asked him: ‘You were acting with supreme self-control and calculation. You were ice-cool, weren’t you?’

McCullum replied: ‘I was not ice cool.’

He was then asked by Mr Cammegh about why, at home he ‘masturbated to porn just a few hours after strangling her, and – we say – trying to cut her head off?’

McCullum replied: ‘I was feeling a bit down.’

Asked if the reason he also followed internet links to killers Levi Bellfield, Peter Sutcliffe, and Ian Huntley was because he was ‘embracing the idea of joining their club’, McCullum replied: ‘No.’

The trial at Leicester Crown Court continues.

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Ross McCullum throttled Megan Newborough then cut her throat after inviting her to his home in Leicestershire on August 6 last year.