Stephen and Carol Baxter were found dead at their home in Essex (Picture: East Anglia News)

A millionaire couple found dead at home in their armchairs had the powerful synthetic opioid fentanyl in their systems, an inquest has heard.

Stephen and Carol Baxter were found unresponsive by their daughter in their home in West Mersea, Essex on Easter Sunday earlier this year.

Police have since launched an investigation into their deaths, with several arrests made.

Paramedics had been called to the Baxter’s home but tragically the couple, who were joint directors of bath and shower mat firm Cazsplash, were confirmed dead at the scene.

Their daughter, who was with her one-year-old son at the time, immediately suspected carbon monoxide poisoning and threw open the bi-fold doors at the property.

But it emerged this week that a post-mortem examination gave a provisional cause of death for Mrs Baxter, 64, as combined fentanyl and promethazine toxicity with terminal bronchopneumonia.

Fentanyl is a powerful synthetic opioid which is similar to morphine but up to 100 times more potent.

It is a prescription drug that is also made and used illegally – often as a substitute for heroin.

An investigation has been launched by Essex Police, who yesterday said the deaths were initially treated as unexpected but not suspicious.

The home of Stephen and Carol Baxter in West Mersea, Essex (Picture: East Anglia News Service)

A spokesperson added: ‘As a result of an extensive investigation and toxicology analysis, two men and a woman were arrested in order to gain comprehensive accounts from them.

‘They remain in custody for questioning as other enquires are conducted.

‘We continue to remain open-minded as to how the couple died.’

At the inquest this week, the provisional cause of death for Mr Baxter, 61, was delivered as cardiomegaly and alcoholic liver disease with fentanyl intoxication.

Area Coroner Sean Horstead said: ‘On the basis of the information I am satisfied that this requires a full inquest.

‘At the written request of Essex Police, I will suspend the coronial investigation for four months.

‘That will run until Monday, November 6, 2023, no doubt there will be communication from Essex Police from the expiry of that date.

‘I offer my sincere condolences to the friends and family of [the Baxters] during this very difficult time for them.’

The couple founded Cazsplash, which sells corner and curved shower mats, in 2012.

Mrs Baxter had run the business since its inception, having also worked in adult education, while Mr Baxter worked for a real estate firm.

The duo were also both keen members of West Mersea Yacht Club, in Coast Road, which flew its flag at half mast following their deaths as a mark of respect.

Mersea resident John Akker told the Gazette it was a ‘shock to locals’, adding: ‘It is very sad news.’

Stephen and Carol Baxter were found unresponsive by their daughter Ellie Baxter in their home in West Mersea, Essex.