A church warden is accused of sleeping with and murdering a university lecturer before trying to kill a retired headmistress to benefit from their wills.
Baptist minister's son Benjamin Field, 28, aided by magician Martyn Smith, 32, plotted the deaths of churchgoers Peter Farquhar, 69, and Ann Moore-Martin, 83, jurors at Oxford Crown Court were told.
Field had undergone a "betrothal" ceremony with gay Mr Farquhar while also having a string of girlfriends and was in a sexual relationship with spinster Miss Moore-Martin, who was 57 years his senior.
The pair "psychologically manipulated" - also known as ‘gaslighting’ - the retired teachers, who lived three doors from each other in the picturesque village of Maids Moreton, in Buckinghamshire, making them believe they were losing their minds and left so desperate would kill themselves, the court heard.
Field also produced a list of local elderly "clients" whose homes he burgled and included a 101-year-old woman who he planned to deceive, jurors heard.
They pair are accused of murder, conspiracy to murder and fraud, while Field's younger brother Tom, 24, also faces an allegation of fraud.
Mr Farquhar, a former English teacher, author and part-time lecturer, died in October 2015 while retired teacher Miss Moore-Martin died in May 2017.
Oliver Saxby QC, prosecuting, told the jury Benjamin Field's "project" was to befriend someone vulnerable, get them to change their will and then "make sure they died”.
"The motive was financial gain - laced, as far as Benjamin Field is concerned, with a profound fascination in controlling and manipulating and humiliating and killing," he said.
Mr Saxby alleged that Benjamin Field suffocated Mr Farquhar and tried to kill Miss Moore-Martin "by a manner of means". The spinster later died from natural causes.
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Smith was "enthralled" by Benjamin Field and became "greedy" while assisting him.
The court heard that Tom Field, a Cambridge University music student, was on the "margins" of the alleged fraud.
He is accused, alongside his brother and Smith, of claiming he was seriously ill to defraud Miss Moore-Martin of £27,000 to buy a kidney dialysis machine.
Benjamin Field and Smith met while both studying English at the University of Buckingham, where they were taught by Mr Farquhar, who was "torn" by his sexuality believing it incompatible with his Anglican beliefs.
As Benjamin Field and Mr Farquhar's relationship developed, they underwent a "betrothal ceremony", which the pensioner described in his handwritten journal as "one of the happiest moments of my life". His writings also suggest their relationship had become sexual.
Like Mr Farquhar, Miss Moore-Martin was also unmarried, never had children, was a practising Roman Catholic and also "intensely private”.
Mr Saxby alleged Benjamin Field and Smith secretly gave Mr Farquhar sedatives and psychoactive substances and encouraged him, as a social drinker, to drink more whisky - giving the impression to the outside world he was an alcoholic - "a dribbling shambles of his former self”.
After Mr Farquhar died a coroner concluded his death as alcohol-related and Benjamin Field and Smith collected their inheritance. Benjamin Field received £20,000 and a life interest in Mr Farquhar's home and Smith got £10,000.
By which time, they had targeted Miss Moore-Martin.
"Benjamin Field and Ann Moore-Martin became friends. Again, they entered into a relationship - one that was undoubtedly sexual," Mr Saxby said.
Benjamin Field and Smith also embarked on a "campaign of 'mirror writing'" - leaving messages for Miss Moore-Martin in her home, which she believed were from God.
She later suffered a seizure and was admitted to hospital where she confided in her niece - prompting a police investigation.
Detectives later recovered a copy of the novel, Young Poisoner's Handbook, which Benjamin Field owned, a booklet entitled, End Of Life, and found an Amazon receipt for a copy of The Five Last Acts - a book about planning suicide.
Benjamin Field and Smith deny charges of murder, conspiracy to murder and possession of an article for the use in fraud.
Field, of Wellingborough Road, Olney, Buckinghamshire, also denies an alternative charge of attempted murder. But he has admitted four charges of fraud and two of burglary.
In addition Smith, of Penhalvean, Redruth, Cornwall denies two charges of fraud and one of burglary.
Tom Field, also of Wellingborough Road, Olney, Buckinghamshire, denies a single charge of fraud.
The trial continues today.