Peter Farquhar, 69, a retired university lecturer was presumed to have died of natural causes when he died at his home in the village of Maids Moreton, near Buckinghamshire, in October 2015.
However Thames Valley Police became suspicious when his 83-year-old neighbour Ann Moore-Martin - who lived three doors away, also died suddenly after a short illness 18 months later.
Mr Farquhar's lodger, Ben Field, 27, a church warden, and friend 31-year-old Martyn Smith, a magician, have been named locally as two of three men arrested as part of the double-murder probe.
Field who was a former English and journalism student was arrested for murdering the pensioners, attempting to defraud them and also burglary.
He had been the deputy church warden at Stowe Parish Church, where Mr Farquhar attended and was also a lay preacher.
It is understood that both men helped look after Mr Farquhar as his health deteriorated in the final months of his life.
They also set up a company with Mr Farquhar, called Farquhar Studies Ltd, in order to publish the academic's work.
An article published in August 2015 on the Buckinghamshire and Winslow Advertiser website, covered a local book signing at Stowe House for the release of Mr Farquhar's third novel "A Wide Wide Sea".
It states: "The book is finally seeing the light of day thanks to two students from the University of Buckingham, Ben Field and Martyn Smith who discovered the handwritten manuscripts and persuaded Mr Farquhar to publish it."
Channel 4 News political correspondent Michael Crick, who was taught by Mr Farquhar at Manchester Grammar School and who remained life-long friends with him, said he was shocked by the police investigation.
He said: "Peter's death was very sudden and sad and it is all the more distressing that police are treating it as a possible murder.
"He was a very inspirational teacher to whom I owe a lot. He was somewhat of a father figure to many of us."
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