Detectives investigating the death of a woman whose husband was later convicted of killing his fiancee have arrested a man on suspicion of murder.

Police said a 57-year-old man from Bedford was detained on Tuesday in connection with the death of Diane Stewart in Bassingbourn, Cambridgeshire, eight years ago.

Mrs Stewart, 47, was found dead in the garden of her home on June 25 2010. An inquest at the time concluded she had died of natural causes from a “sudden unexpected death in epilepsy”.

Police announced a re-investigation into her death last year after her husband, Ian Stewart, was convicted of murdering children’s author Helen Bailey.

On Wednesday, Hertfordshire Police said the arrested man had been released under investigation.

A spokesman said: “Detectives from the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit have arrested a man following a re-examination of 47-year-old Diane Stewart’s death at her home in Bassingbourn on June 25 2010.

“The 57-year-old man from Bedford was arrested on Tuesday August 21 and questioned on suspicion of murder before being released under investigation.”

Stewart was jailed for 34 years at St Albans Crown Court for smothering Ms Bailey.

The court was told Stewart spent weeks poisoning his bride-to-be with prescription sedatives before smothering her in a plot motivated by greed.

The Electra Brown writer was dragged into a cesspit deep below the couple’s luxury home, where she remained hidden for three months.