Last year, church warden Benjamin Field was convicted of murdering Mr Farquhar in 2015, after a gaslighting campaign of physical and mental torture.
Field, 29, was jailed for killing Mr Farquhar, 69, in order to inherit his house and money. However, he was acquitted of the attempted murder of neighbour Ann Moore-Martin.
The true crime drama will “explore the death of Peter Farquhar in the village of Maids Moreton, Buckinghamshire, and the extraordinary events that unfolded over the following three years.”
Writer Sarah Phelps, who also penned the BBC adaptation of And Then There Were None, said: “This is such a shocking and brutal case – how a murderer hid his manipulation and malevolence in plain sight of a small community, how he insinuated his way into the lives of his victims.
“It’s a heartbreaking story of such desperate longing and loneliness. But even within the darkness, there is the most astonishing blazing love and courage.
“I’m honoured to have been asked to write this drama and to be trusted with the memories and experiences of Peter and Ann’s families.”
Executive producer Brian Woods said: “The families of both Peter and Ann agreed to support this powerful story being serialised.
“This drama will show how these two vibrant and complex souls were groomed and manipulated by an evil predator.
“And we hope this series will raise awareness of how vulnerable those living alone can sometimes become.”
Casting for the mini-series is yet to be announced.