A multi-millionaire property developer made a shopping list of items to use when he murdered his escort girlfriend, a court heard.
Peter Morgan, 54, is accused of strangling Georgina Symonds, 25, after discovering she planned to "fleece him", leave him and work for other men.
The father-of-two, from Llanellen, near Abergavenny, lavished Miss Symonds with expensive gifts and paid her up to £10,000 per month to be his personal escort.
He planted a listening device disguised as a white plug socket in a bungalow he owned in Llanmartin, Newport, where he allowed the mother-of-one to live rent-free.
Newport Crown Court heard Morgan used the device 514 times from November 2015 until Miss Symonds' death on January 12.
On the evening of January 10, he overheard Miss Symonds telling new boyfriend Tom Ballinger that she planned to leave married Morgan and blackmail him.
The court heard she threatened to tell Morgan's family how she had met him and had a photograph with him and another escort in the martial home.
Prosecuting, William Hughes QC told the jury that Morgan, who denies murder, created a list on his phone at 3.20am the following morning.
The list, entitled 'String' read: "String, 02, poly, glove, snip, handle, tape, Special K, starter, rag, adapter".
"It mirrors the items found by the police that had been used to kill, conceal and transport Georgina's body," Mr Hughes said.
"It is highly probative of Peter Morgan's planning and pre-meditation in the killing of Georgina."
The jury heard Morgan strangled Miss Symonds with twine, then wrapped her body in polythene sheeting which he attached to a metal pole so he could carry it easily.
Her legs were bound with tape to fit in the boot of his white Porsche Cayenne, which he used to transport her to an outbuilding close to his estranged wife Helen's home.
Morgan, who is worth £20m, later told police: "Premeditating a murder isn't something you do lightly, I can tell you."
He said he had taken the items to the two-bedroomed bungalow on the morning of January 12 after overhearing the conversation between Mr Ballinger and Miss Symonds.
"When he had the twine around her neck, he told her that she had been right about him bugging the home," Mr Hughes said.
"When he released the tightness of the twine the first time Georgina had said 'You're gonna pay for this now'. She couldn't move.
"He pulled it tighter again. He'd hoped Georgina would say she was sorry, Georgina might have repeated that he was going to pay.
"That wasn't the answer he was looking for. At that time, Peter Morgan said he was thinking 'I've got to kill her'."
Morgan then drove to Beech Hill Farm in Usk, Gwent, where his wife and two daughters lived, and left Miss Symonds' body in an outbuilding at 12pm.
Miss Symonds was reported missing to police after she failed to collect her five-year-old daughter from school that afternoon.
Morgan confessed to two police officers at 4.45am on January 13, telling them: "I strangled her this morning. I love her so much."
Officers discovered Miss Symonds' body at 6am. A post-mortem examination found she died from strangulation.
In the interviews, Morgan described himself as Miss Symonds' "sugar daddy" and said he spoiled her.
He had been in a relationship with the keen horse rider for three-and-a-half years and paid her between £7,000 to £10,000 per month not to see other men.
The court heard Miss Symonds had undergone two breast augmentations and full body liposuction costing £8,000, which Morgan had paid for.
Morgan claims he has Asperger syndrome and killed Miss Symonds following a "loss of control" after overhearing the conversation between her and Mr Ballinger.
"This was a much older man completely besotted and infatuated with a younger woman," Mr Hughes told the jury.
"A man who was obsessed, smitten and perhaps in love, who decided in the most cold-blooded way that if he was not to have Georgina, then no-one else would."
Deborah Symonds, the mother of Miss Symonds, described her as a "lovely, fun, happy girl".
"She loved money, she loved the finer things in life," she told the jury.
Mrs Symonds said her daughter and Morgan were happy until her ex-boyfriend killed himself in November 2015.
On the morning of January 12, she received a call from a crying Morgan who said: "She doesn't want me anymore".
The trial continues.