Officers are searching two properties Northamptonshire as part of an investigation into the deaths of two pensioners.
A 22-year-old man from Milton Keynes has been arrested as part of the investigation into the deaths of two neighbouring pensioners.
Detectives in Milton Keynes swooped on the house at dawn and are currently searching it.
The man has been arrested on suspicion of committing fraud by false representation and also for conspiracy to defraud.
Two other men, aged 31 and 27, have been arrested as part of the same investigation on suspicion of two counts of murder plus conspirary to defraud and burglary.
As well as the Milton Keynes property, three others are also being searched by officers - two in Towcester and one in Cornwall.
The alleged victims are retired schoolteacher Peter Farquhar, 69, and 83-year-old Ann Moore-Martin.
The pair lived in the same street in the affluent village of Maids Moreton, 12 miles away from Milton Keynes.
Mr Farquhar, a prominent churchman and former English teacher at the private Stowe School, died in 2015.
At the time it was believed he had passed away in his sleep.
Ms Moore-Martin lived a few doors away and died in May last year. It was her death which sparked an initial police investigation and was later handed over to the Thames Valley Police Major Crime Team.
Detectives were understood to be carrying out toxicology tests on Ms Moore-Martin’s remains to try to establish how she died.
A spokesman for Thames Valley Police confirmed today that officers had made three arrests in connection with the murder investigation.
He said: “The investigation is in relation to the deaths of two residents of Maids Moreton near Buckingham in Buckinghamshire: Peter Farquhar died on October 26 2015, aged 69 years and Ann Moore-Martin died on May 12 2017, aged 83 years.
“The causes of death are yet to be determined.
“As part of the investigation four properties are currently being searched. These include one property in Milton Keynes, two properties in Towcester, Northamptonshire, and an address near Redruth, Cornwall.”