The Murdering Mastermind of Mersea

The Shocking Case of Luke D’Wit and a Decade of Deception

Joni E. Johnston, Psy. D.
10 min readApr 2, 2024
courtesy of Trip Advisor, 2019

When a seasoned detective superintendent describes a murderer as “one of the most dangerous men I have ever come across,” I take notice. After researching this case, I agree. After reading this article, you will, too.

The Backdrop

Come with me to Essex County in southern England. Its geography-bound by the North Sea to the east and London to the southwest-is a land of contrasts, where the hectic energy of urban life collides with the tranquility of the countryside. Chelmsford is the county seat, an enchanting mixture of a modern British city and historic charm. And to the east, along the Blackwater Estuary, lies the coastal town of West Mersea.

West Mercea is a small town. 2011, it had just over 7,000 residents, and the population hasn’t changed much. It’s known for its oysters, sailing culture, resilient residents, and close-knit community. But in 2023, that trust was shattered when a seemingly kind and helpful resident was unmasked as a cold, calculating killer.

The Baxters and Luke D’Wit

In 2023, Luke D’Wit, a 34-year-old IT consultant, had been a familiar face in West Mersea all his life. He grew up here, the only child of “dustman” Vernon D’Wit and his wife, Jan. (From what I can gather, a dustman is the U.S. equivalent of a sanitation worker). After graduating from Thomas Lord Audley School in nearby Colchester, he earned a computer technology degree from the University of Essex.

courtesy of Essex Police Department

It was at this time that D’Wit seemed to stumble. While other young West Merseans were jumping ship for a more exciting, bigger city, D’Wit floated from job to job until he and one of his few friends started a website design company called Stand Out Studios, Ltd. He was twenty-two. But that, too, failed after seventeen months.

So, here he is, in his mid-twenties, single, living with his parents, and floundering. Because he had little interest in girls or booze, he avoided places where other mid-twenty-somethings might congregate and, instead, focused on his interest in IT. He began designing and developing websites for local businesses. He volunteered to help some nonprofits with their website design, a gesture that was both appreciated and business-savvy. He soon became known for his willingness to lend a hand, whether volunteering at local events or offering his technical expertise to those in need.

In 2012, he met Stephen and Carol Baxter, a couple in their fifties who had recently relocated from London and were working hard to promote their new shower mat business, Cazsplash. A mutual friend introduced them. A former adult educator, Carol had devised the ingenious idea to create bath mats that fit around curved or cornered shower units. Stephen, a senior executive with an international property firm, had the business acumen. And their new friend, Luke, had website expertise. It seemed like the perfect trifecta for a successful business.

From Business Partner to Part of the Family

The Baxters’ business thrived, as did their relationship with Luke D’Wit. Sure, some family members thought he was a little odd but nerdy weird, not scary odd. Over time, he became a regular presence in their lives. He told several people that he felt like an “adopted son.” In media interviews and on the stand during the trial, the Baxters’ adult daughter, Ellie, said he became like a brother. Harry, the Baxters’ son, considered him a close friend.

He continued to live with his mother but spent more and more time with the Baxters. He became much more than a business consultant. He often accompanied Carol on walks and to the gym. He joined the family for meals and special occasions. When his dad died in 2021, the Baxters wrapped their arms around him even more, especially when he disclosed that he had been diagnosed with bone cancer. They were happy to work around his chemotherapy appointments scheduled for every Thursday. They were sympathetic to his treatment-related fatigue and headaches.

D’Wit wasn’t the only one with health problems. In 2005, Carol was diagnosed with Hashimoto’s Thyroiditis, a chronic autoimmune condition in which the thyroid fails to produce hormones that play an essential role in metabolism and other bodily functions. It most typically develops in middle-aged women, and symptoms (such as severe fatigue, weight gain, dry skin, joint stiffness, depressed mood, and muscle pain) tend to wax and wane.

As a friend and fellow health sufferer, D’Wit became invested in helping Carol deal with her health challenges. He dove into the research about effective treatment and online resources. He tracked down a Florida doctor who specialized in Hashimoto’s disease. He investigated nutritional supplements and invented a vitamin-enriched health drink that he would prepare for her. He hooked her up with other women who shared Carol’s diagnosis; these women supported Carol online and exchanged phone messages. He gradually became Carol’s primary source of medical information. Pretty soon, he was the only one.

The Devil in Disguise

No one knew Luke D’Wit. For years, while pretending to love and care for his “adoptive parents,” he had been carefully constructing an elaborate web of lies and deceit to manipulate and control them. It is unclear exactly when this started; some sources say it started as early as 2014.

He created a series of fake online identities, which he used to communicate with Carol and her daughter, Ellie. Playing on Ellie’s dreams of becoming a professional singer, he pretended to be “Jenny,” a theater producer who promised to help her further her singing career. “Jenny” requested several songs from Miss Baxter, including “I’d Do Anything” from the musical Oliver!, which she recorded with the assistance of — of course — D’Wit.

D’Wit created a total of seven fake personas, each with their own backstory and role in his twisted scheme. One of the most diabolical was Dr. Andrea Bowden, the alleged Hashimoto specialist, who bombarded Carol with misinformation and bad medical advice. The “health drinks” he prepared for her were concoctions laced with a dangerous cocktail of drugs that exacerbated her condition. He connected her with a network of fictitious Hashimoto sufferers. He even went so far as to send Carol voice memos in which he impersonated a woman named Jenny, one of the fictitious patients. Even D’Wit’s cancer diagnosis was fake, designed to garner sympathy and pity.

D’Wit slowly began to isolate Carol from her natural support system, making her increasingly dependent on him and his fabricated world. And the sicker she got, the tighter his grip became. Over two years, Carol’s health deteriorated. She lost weight, became weak and fatigued, and struggled with memory problems. She went from a vibrant, active woman into a shadow of her former self. “Dr. Bowden” soon began prescribing health tonics for Stephen. All the while, D’Wit played the role of the concerned friend, offering support and comfort even as he continued to poison them.

The Final Act

During a hospital visit in January 2022, doctors discovered a metal tack inside a medicine capsule in Carol’s colon. Doctors were dumbfounded; they had no idea how it had gotten into Carol’s system. No one suspected D’Wit.

But there were signs that the relationship between D’Wit and the Baxters was fraying. By the end of 2022, Ellie said that tolerant parents were getting tired of D’Witt showing up uninvited almost every day. His intrusiveness was starting to annoy the Baxters. Ellie claimed her parents had even talked about changing their passwords and making a clean business break with D’Wit. It wasn’t that they didn’t want to have any relationship with him; they just wanted some space. Perhaps this is why, on April 7, 2023, D’Wit made his final move. On April 7, 2023, under the guise of administering a liver cleanser, he administered lethal doses of the powerful opioid fentanyl to both Stephen and Carol.

The Discovery and the Investigation

The following day, Easter Sunday, Ellie found her lifeless parents sitting in their favorite armchairs. In a twisted display of concern, D’Witt, who had just treated his mother to breakfast and ice cream, D’Wit arrived at the Baxters’ home shortly after Ellie’s discovery. Calmly taking the phone from a hysterical Ellie, he told a 999 operator that he was a friend of the couple and that he always popped in to check on them. However, his real goal was to control the narrative and deflect suspicion from himself.

He told officers he had left their address at 7.55 p.m. two days previously, just as they sat down to dinner. Carbon monoxide was the immediate suspect because they had no visible injuries; however, fire officials quickly ruled it out. Investigators were determined to get some answers. An analysis of Mrs. Baxter’s pacemaker gave them somewhere to start; data estimated that she had died sometime between 11:00 a.m. and 2:00 p.m. on April 8.

Just a day after their bodies were discovered, their will was rewritten on D’Wit’s phone, leaving him as the “director and person with significant control” of their business. It added that all decisions should be directed to him. He placed a copy of this document in the house, where Ellie found it. He gave another copy to Cazsplash Limited’s landlady.

Ironically, it may have been D’Wit’s last online persona, solicitor Martin Ellison, that led to his unmasking. The fake solicitor’s role was to help legitimize the fake will that D’Wit had created to gain control of the Baxters’ estate. Experienced solicitors have seen the ugly side of wills and money, and when it came to pulling the wool over one’s eyes, “Martin Ellison” was not up to the task. D’Wit’s status skyrocketed from witness to suspect.

What gradually came to light was truly one of the most heinous crimes I have encountered in terms of betrayal of trust and premeditated predation. A search of D’Wit’s home revealed a trove of incriminating evidence, including fentanyl patches, metal tacks matching those found in Carol’s body, and dozens of electronic devices he had used to perpetrate his elaborate hoax. A toxicology report found that a fentanyl overdose was the cause of the Baxters’ death; prosecutors believed it came from a prescription prescribed for D’Wit’s father before his death.

There were other drugs involved. Pills containing quadruple doses of promethazine were also found. Promethazine is a particularly cruel drug if taken in excess or unwittingly because it causes worrying cognitive changes similar to dementia or a stroke. Carol thought her Hashimoto’s disease was progressing. She was scared. Her friends and family were worried; they were watching her waste away.

The fact that D’Wit had four times the usual dose in each pill suggests that he wanted his victims to believe they were taking much smaller doses than they were. Most chilling was the discovery of a hidden camera that D’Wit had installed in the Baxters’ home, which allowed him to monitor a camera from the couple’s conservatory. During the final moments of their lives, he watched on his phone as the Baxters first became incapacitated by the drugs and then died. He had pictures of the dead couple on his phone.

The Trial and Its Aftermath

D’Wit pleaded not guilty and denied almost everything. He did admit to the fake online identities — how could he not — but he insisted that Stephen Baxter was both a collaborator and instigator. “He wanted to give her someone to talk to.” Of course, the one-way nature of the email messages easily discredited this defense.

Prosecutors meticulously outlined the extent of D’Wit’s deception, from the fake doctor persona he used to manipulate Carol to the health drinks he had laced with deadly doses of fentanyl. They played seized recordings of D’Wit practicing the voices of his various fake personas, showing just how calculated his crimes were.

They painted a picture of a man driven by greed and a twisted desire for control, someone who had carefully groomed the Baxters over a decade to gain control over their lives and access to their finances.

Even the judge was outraged. During sentencing, the judge spoke of the “cruel and senseless nature” of D’Wit’s actions, his meticulous planning and callous disregard for the suffering he caused, the devious nature of his damaging medical advice, and his twin motives of money and a sadistic form of control.

In March 2024, Luke D’Wit was found guilty of the murders of Stephen and Carol Baxter. He was sentenced to life in prison with a minimum term of 37 years, an extremely severe term in the U.K. and one that reflected the callous nature of his crimes.


So what are we to make of the horrific tale?

Are there any lessons to be learned that won’t lead us down a path filled with cynicism and rage? I don’t know what good has come out of this tragedy other than the capture of a man whom investigators believed was fully capable of striking again. Because of Stephen and Carol, Luke D’Wit will not harm anyone else.

Detective Superintendent Rob Kirby of the Kent and Essex Serious Crimes Directorate was the hero who started this story with his somber description of the dangerousness of Luke D’Wit. After the trial, he stated, “I have absolutely no doubt that had he not been caught, he would have gone on to commit further murders.”

That’s a small consolation prize for Harry and Ellie. Hopefully, their parents’ legacy will comfort them as they navigate a new reality. And, hopefully, one day, we psychologists will be able to understand better the path that perpetrators like Luke D’Wit travel so we can intervene before someone gets hurt.



Joni E. Johnston, Psy. D.

Forensic psychologist/private investigator//author of serial killer book. Passionate about victim’s rights, the psychology of true crime, and criminal justice.