It is understood that a detective inspector and two sergeants from the Devon and Cornwall force are to question Margaret Harris, whose 62-year-old husband, Clifford, apparently committed suicide in the Swan river in Perth, Western Australia, on Wednesday.
Police believe Mr Harris, a retired teacher and bee enthusiast from Ebberly in north Devon, may have been having an affair with Janice Crompton, 58, an art teacher, who lived alone in a remote former coaching house at Chelfham, near Barnstaple, north Devon.
Neighbours said he had been a regular visitor to the home of Mrs Crompton, who kept animals, and had beehives, and whose husband lived in Cyprus.
Her body was found on 25 January - three days after she was reported missing. Wrapped in a duvet and polythene bags, her body was discovered in the back of Mr Harris's red Toyota pick-up truck which had been parked at his son-in-law's farm at Knowstone, near South Molton, north Devon.
A hive of bees was placed on top of the body.
Detectives are also to examine medical records to establish whether or not Mr Harris suffered a rheumatic problem which may have prevented him from lifting the body into the truck alone.
A police spokesman said yesterday that detectives had information that Mr Harris was fit and healthy, and that he was responsible for clearing land next to Mrs Crompton's home.
But other people had said that he was unable to lift things and required help "so certainly we will be looking at medical records, although they may not tell us the whole story", the spokesman added.
Mr Harris's truck was parked at the farm early on Wednesday, 22 January - the day he and his wife were seen waiting for a train at Tiverton station, east Devon, en route to a planned, extended holiday in Australia, where their son Philip lives in Adelaide.
A week later Mr Harris - who was being monitored by Australian police following a request via Interpol from the Devon and Cornwall force - apparently walked a mile from his hotel to drown himself.
John Evans, the Chief Constable, said he had been unable to persuade the Crown Prosecution Service to change its decision not to give permission for the Australian police to arrest Mr Harris.
But the CPS claimed that the West Country force did not produce enough evidence for extradition.
Mrs Harris, 60, was interviewed by Australian police and then released following her husband's death from asphyxia. Australian police said that she had no knowledge of the killing and the search for her and her husband until a news report the day before he died.
Devon and Cornwall police said that from the outset the officer leading the inquiry, Detective Superintendent John Smith, had wanted to talk to both Mr and Mrs Harris. "But it was his van, and he was the one we wanted the explanation from," the spokesman said.
The West Country force has said that it is not looking for anyone else in connection with Mrs Crompton's murder.Reuse content