A churchwarden who murdered an author to inherit his estate has been jailed for a minimum of 36 years.
Benjamin Field, 28, duped 69-year-old Peter Farquhar into a fake relationship to get him to change his will.
Mr Farquhar died in the Buckinghamshire village of Maids Moreton in October 2015 and Field tried to make his death look like an accident or suicide.
The Baptist minister's son was found guilty of murder at Oxford Crown Court in August.
He was also accused of plotting to kill Mr Farquhar's neighbour Ann Moore-Martin, 83, but was found not guilty.
Mr Justice Sweeney said Field was a "well-practiced and able liar", adding: "I have no doubt that you are a dangerous offender."
Field admitted duping both Mr Farquhar and Miss Moore-Martin into fake relationships with him as part of a plot to get them to change their wills, but denied any involvement in their deaths.
Miss Moore-Martin died of natural causes in May 2017.
University lecturer Mr Farquhar and Field had undergone a "betrothal" ceremony while the trial heard Field and former headmistress Miss Moore-Martin had a sexual relationship.
The court heard Field carried out a sustained "gaslighting" plot aimed at making Mr Farquhar question his sanity.
Mr Farquhar's drinks were topped up with bioethanol and poteen, a high strength Irish alcohol, and his food was laced with drugs.
Jurors were told Field "suffocated him" when he was too weak to resist, and left a half-empty bottle of whisky in Mr Farquhar's room to create the misconception he had drunk himself to death.
Mr Farquhar, who taught part-time at the University of Buckingham, had three novels published.
His third book, A Wide Wide Sea, was dedicated to Field, who delivered the eulogy at his funeral.
In an attempt to get Miss Moore-Martin to change her will, Field would write "messages from God" on mirrors around her home.
The deeply religious retired teacher who never married or had children, later changed her will to leave her home to Field.
A consultant psychiatrist said Field "knew exactly what he was doing, in a carefully planned and orchestrated way and was in full control of his own decision making".
In a statement after the sentencing Mr Farquhar's brother, Ian Farquhar, said: "Ben Field is a deeply malevolent and thoroughly evil man who callously and greedily seduced his way into my brother's life.
"His sentence today brings some justice to this horrific event in our family's life. Though of course the wound will always remain
Mark Glover, of Thames Valley Police, said Field was "unlike any other criminal" he had encountered in his 31-year career.
"The extent of his planning, deception and cruelty towards his victims is frankly staggering, and I do not believe he has ever shown an ounce of remorse or contrition," he said.
"If he is sorry for anything it is that he got caught."
Field, of Wellingborough Road, Olney, Buckinghamshire, previously pleaded guilty to four counts of fraud relating to the fake relationships and defrauding Miss Moore-Martin out of £4,000 for a car and £27,000 for a dialysis machine. He also admitted two counts of burglary.
He was sentenced to life in prison and ordered to serve a minimum of 36 years.