The man convicted of killing an author in 2016 and on trial for the murder of his wife six years earlier was accused in court of having his wife cremated “so there would be very little that could come back and bite you”.

Ian Stewart 61, is accused of killing Diane Stewart, 47, at their home in Bassingbourn, Cambridgeshire, in 2010.

Her cause of death was recorded in 2010 as Sudden Unexplained Death in Epilepsy (SUDEP).

Police investigated the case after a jury found Stewart guilty in 2017 of murdering his fiancee, children’s book author Helen Bailey, the year before.

A neuropathologist was asked to examine preserved parts of Mrs Stewart’s brain, which had been donated to medical science.

He said he found evidence of a lack of oxygen to her brain for between 35 minutes and an hour before her death.

Stuart Trimmer QC, prosecuting, told the defendant: “You had Diane Stewart cremated so there would be very little that could come back and bite you.”

Stewart, being cross-examined at Huntingdon Crown Court, replied: “The cremation was a joint decision with the boys and if I was thinking that way I wouldn’t have agreed to keep the brain and heart.”

Mr Trimmer said that Stewart’s 999 call in 2010, in which he said his wife had had a fit, was “just a lying charade”, adding: “You’re a devious man, Mr Stewart.”

Stewart replied: “No.”

During Stewart’s trial for the murder of Ms Bailey, jurors were told her body was discovered in a cess pit at the £1.5 million home she shared with Stewart in Royston, Hertfordshire.

A forensic pathologist found it was most likely she was suffocated while she was sedated by drugs.

Mr Trimmer said: “Is it not very surprising that both Helen Bailey and Diane Stewart are individuals whose death was caused by a similar mechanism in the view of the professionals?”

“Only some of the professionals,” Stewart replied.

The prosecutor suggested Stewart was “a man capable of extreme and callous violence”.

Stewart replied: “No.”

Stewart denies the murder of his wife.

The trial continues.