Detectives have been given extra time to question two men arrested on suspicion of the murder of two retired teachers who lived in the same village street.
Thames Valley Police have launched a double-murder inquiry into the deaths of Peter Farquhar, 69, and 83-year-old Ann Moore-Martin who died a year-and-a-half apart in the village of Maids Moreton, near Buckingham.
Church warden Ben Field, 27, from Towcester, Northamptonshire, and magician Martyn Smith, 31, from Redruth, Cornwall, have been arrested on suspicion of two counts of murder, two counts of conspiracy to murder, two counts of suspicion of fraud by false representation, conspiracy to defraud and one count of burglary.
A force spokeswoman confirmed that police have been granted a custody extension to enable further questioning of the pair.
A third man, aged 22, from Milton Keynes, was arrested on suspicion of conspiracy to defraud, conspiring to commit fraud by false representation and fraud by false representation.
He has been released pending further investigation, the spokeswoman said.
A death certificate has shown that the death of Mr Farquhar, a retired teacher and university lecturer, was ruled as an accident at an inquest held in November 2015 by retired Buckinghamshire coroner Richard Hulett who found that he died of "acute alcohol intoxication".
An inquest has not yet been held into the death of Ms Moore-Martin and police have said the causes of death for the two pensioners were "yet to be determined".
Police have been searching four properties in three locations around the country as part of the inquiry.
Smith and Field, both students at the University of Buckingham where Mr Farquhar was a guest lecturer, helped look after him in the months before he died.
The pair persuaded Mr Farquhar to publish his novels and were planning to make a documentary TV programme about him.
Field, who was Mr Farquhar's lodger, was also a church warden at Stowe Parish Church where the retired teacher was a lay preacher.