LONDON (AP) — The partner of British children’s author Helen Bailey was convicted Wednesday of killing her and dumping her body in a cesspool in a financially motivated murder.

A jury at St. Albans Crown Court, north of London, found Ian Stewart guilty of murder, fraud, perverting the course of justice and preventing a lawful burial. He will be sentenced Thursday.

Police said after the verdict that they would re-examine the 2010 death of Stewart’s first wife. At the time it was ruled to be unexpected but from natural causes.

The body of 51-year-old Bailey was found in July in a cesspool under the garage of the home she shared with Stewart, alongside the body of her miniature dachshund Boris. Stewart had reported Bailey missing three months earlier.

Bailey created the Electra Brown and Daisy Davenport series of novels for teenagers, and wrote a blog called Planet Grief after her husband of 22 years drowned during a Caribbean holiday in 2011.

She later met Stewart through a Facebook group for bereaved people. They began a relationship, and he became the chief heir to Bailey’s fortune and gained power of attorney over her affairs.

Prosecutors said Stewart drugged Bailey over many weeks with his prescription anti-insomnia drug, possibly by slipping it into her morning scrambled eggs.

She grew alarmed by her deteriorating state of mind, searching online for terms such as “can’t stop falling asleep” and expressing concern to loved ones.

Prosecutors said Stewart likely smothered Bailey with a pillow when she was sedated to gain her 3.3 million-pound ($4.1 million) estate.

Charles White of the Crown Prosecution Service said Stewart “murdered Helen Bailey and then conducted a cynical, deceitful and calculated charade as he watched the police conduct a futile missing person investigation.”

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