THE predatory partner of North-East children’s author Helen Bailey has been found guilty of drugging and killing her as part of a plot to acquire her riches.

Driven by greed, Ian Stewart spent months poisoning the Electra Brown writer with sedatives, smothering her last April once she was stupefied.

The lifeless 51-year-old was dragged into a foul cesspit hidden below their luxury Hertfordshire home, where her body lay undiscovered for three months.

Following a six-week trial at St Albans Crown Court, a jury yesterday found the 56-year-old, of Royston, Herts, guilty of murder, fraud, three counts of perverting the course of justice and preventing a lawful burial.

Police said the “sudden, unexpected” death of Stewart’s first wife, Diane - found in the couple’s garden in 2010 - will now be re-examined.

Stewart scoped out the vulnerable widow on the internet in 2011 - earning his way into her trust and £3.3m estate. They met on a Facebook group for the bereaved and began a relationship within a year of Ms Bailey’s first husband drowning on holiday.

“She was being grossly deceived by someone who was preying on her,” prosecutor Stuart Trimmer told his trial.

Over many weeks, Stewart surreptitiously fed Ms Bailey, who was brought up in the village of Ponteland, near Newcastle, his prescription anti-insomnia drug, Zopiclone, possibly by lacing her morning scrambled eggs.

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

A pillowcase found next to her body led the prosecution to suggest Stewart used a pillow to smother her while she was sedated.

Ms Bailey, known for her young adult stories and memoir on bereavement, was finally found submerged in a tank of human sewage beneath the couple’s garage on July 15 last year. Her beloved dog Boris was found dead at her side.

The author’s family welcomed the verdict, but said her death left them lingering in a “long shadow of loss”.

Stewart sparked a major search after telling Ms Bailey’s loved ones that she had left abruptly to seek some “space” at her seaside cottage in Broadstairs, Kent.

Detective Chief Inspector Jerome Kent said: “To kill somebody was despicable enough, but to dispose of her in the way he did and lie to everyone including his own children shows how wicked and despicable that man is.”

A financial inquiry will ensure former software engineer Stewart, who is to be sentenced at 10am this morning, does not profit from the crime.