Luke D'Wit was found guilty of killing Stephen Baxter, 61, and his 64-year-old wife Carol - and rewriting their will to take charge of their shower mat and bathroom company.

The 34-year-old worked for the couple and is said to have described himself as "almost like a son" to them.

The Baxters were discovered at their home by their daughter Ellie on Mersea Island in Essex on Easter Sunday last year.

D'Wit arrived soon after and described himself as their "friend" to a 999 call handler as he gave a false account, while Ellie was heard in distress in the background.

Fentanyl - an extremely strong synthetic opioid about 100 times stronger than morphine - was found in their bodies.

D'Wit, who had denied murder, was convicted after jurors reached a unanimous verdict at Chelmsford Crown Court following a trial which lasted more than a month.

He had created a gallery of fake personas to manipulate them - posing as a doctor from Florida and members of a fake support group for the thyroid condition Hashimoto's, which Mrs Baxter suffered from.

Prosecutors said that a total of seven fake personas were created - and D'Wit had been drugging Mrs Baxter for a while, making it appear like she suffered from dementia or a stroke.

Tracy Ayling KC said the pain he had inflicted on her was for his own satisfaction - and D'Wit had previously tried to harm Mrs Baxter by giving her a pill with a tack inside it.

Prosecutors said a day after the Baxters were found dead, D'Wit created a fake will on his phone that made him a director of their company Cazsplash.

The couple's daughter had said in evidence her parents believed D'Wit was "weird, but nerdy weird".

She said he had initially been brought into their shower mat business in about 2012 or 2013 to "help build the website" before eventually coming round to their house "every day".

Reading her victim impact statement at Chelmsford Crown Court, she said D'Wit had "lied his way into our lives".

She described her parents' killer as a "man so manipulative he hacked his way into our lives over a decade ago, schemed and thoroughly planned my parents' demise".

Ms Baxter added: "They just decided he was lonely, especially after Luke's dad died.

"They took him under their wing and would let him join in."

Describing the moment she found her mother and father dead, she said: "I have never known an emotional pain to physically hurt so much.

"It was like my insides were on fire. I screamed and I screamed."

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In a statement released through Essex Police, their son Harry said: "I feel great sadness looking back on the videos of her when she was acting strangely and seeing him in the background giggling and smiling knowing he's the one inflicting this pain as we were all dolls in his dollhouse, victim to his manipulation.

"Our life will forever be punctured by the gravity of his actions."

Detective Superintendent Rob Kirby said D'Wit was "without doubt one of the most dangerous men I've ever experienced in my policing career".

He added: "I have absolutely no doubt that had he not been caught, he would have gone on to commit further murders."