A lab assistant who is accused of strangling a colleague to death before he dumped her body in a country lane showed nude photos of her to colleagues in the lead-up to the killing, a court heard.
Ross McCullum, 30, admits the manslaughter of 23-year-old Megan Newborough by strangling her at his home in Windsor Close, Coalville, on Friday 6 August, last year.
However prosecutors claim he attacked Ms Newborough, 23, in the living room of the home he shared with his parents before cutting her throat with a carving knife to "make sure she was dead".
In a bid to cover his tracks, the trial heard how McCullum went on to bundle Ms Newborough, who he'd been in a relationship with for around a month, into her own car and drove to a remote rural location near the village of Woodhouse Eaves, Leicestershire.
The 30-year-old accused denies murdering her, however, instead claiming he "lost control" after a sexual encounter between the pair triggered an episode of post-traumatic stress disorder (PTSD) linked to him having been abused by older children when he was a youngster.
Leicester Crown Court also heard how McCullum confided in a co-worker about suffering sexual abuse as a child.
The jury has heard how the victim and accused were co-workers at Ibstock Brick, in North West Leicestershire.
The pair had struck up a "relationship of sorts" after Ms Newborough was involved in carrying out an audit of the company's laboratory, where McCullum worked, earlier that summer.
Joe Howard, senior lab technician at Ibstock Brick, told the court that he had been responsible for training the defendant and overseeing some of his work as a lab assistant.
He recalled Ms Newborough and McCullum "flirting with each other" while her and a HR colleague were carrying out a data protection and privacy assessment involving paperwork and files stored by the lab.
Mr Howard said that he later became aware that the pair had become an item.
He said: "There was a time I observed Ross and Megan at work, I think it was throughout July, last year.
"Megan would come into the lab and they were almost acting like a couple. On occasion, I caught them hugging and kissing in the lab itself."
Mr Howard said the defendant was a reliable worker, however, he recalled his behaviour deteriorating markedly when he was not taking medication prescribed by a doctor for attention deficit hyperactivity disorder (ADHD).
He said: "He mentioned he had ADHD and had medication for it. When he forgot to take it, I observed his behaviour change."
"He said this took the form of "immature" and "teenage-like" behaviour. He became very boisterous.
"He would be swearing at people and start using highly inappropriate language."
Mr Howard recalled McCullum telling him that he and Megan had, on one occasion, had sex together at a pond in countryside close to their place of work.
He told the jury that the defendant had also shown him nude photographs of Megan on his phone which he felt had been "inappropriate".
On one occasion, the lab technician said McCullum confided in him about being the victim of sexual abuse as a child.
"The conversation had been about relationships and houses," he said.
"This led to him outright telling me that he was raped as a kid.
"He said he was taken into a wooded area by a family friend who was looking after him. He said that he was forced to strip naked and perform sex acts on this person."
Mr Howard added: "My response was that he was brave for talking about it and that I would support him. It was a deluge of information from him. I eventually forced him to stop because it was upsetting me."
The court previously heard that Ms Newborough and McCullum had arranged to meet at his house for a sexual encounter on the night of her death while his parents were out.
But the prosecution allege that Megan was dead within 40 minutes of arriving at the address shortly after 8pm.
The prosecutions further allege the defendant, who did not have a driving licence, loaded Megan's body into her white Citroen C3 and dumped her partially-clothed body in thick undergrowth off Charley Road, a remote country lane near Woodhouse Eaves and Beacon Hill Country Park.
Earlier, prosecutors claim he had discarded her phone in Hermitage Road, Whitwick.
The court heard he left her car in the car park of Loughborough College and the jury has been shown CCTV footage of the defendant disposing of Megan's boots, spectacles and other personal items, as well as bloody sheets and other incriminating evidence in nearby bins.
Ms Newborough was reported missing by her family the following afternoon, Saturday 7 August 2021, after she failed to return home.
Her body was found in the early hours of the following day.
The trial continues.