Before her murder, Julie wrote down her worst fear. It came true.

When Julie Jensen was found dead in her Wisconsin bedroom in December 1998, it initially looked like a tragic but natural death.

But then her neighbour produced a letter that changed everything.

Written just days before her death, the mother-of-two had predicted her own murder — and named her "first suspect" if she were to be found dead.

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On December 3, 1998, Mark Jensen called 911 to alert authorities to a tragic discovery. He said he'd found his wife's body in bed, under the covers, still wearing a T-shirt and underwear.

She had no obvious injuries and a medical examiner at the scene initially believed she'd died from natural causes, according to NBC's Dateline.

But there were odd details that stood out. Julie appeared to have been rolled on her side and even though she was so sick she'd complained of breathing problems, Mark had left her alone all day.

Then, the police made another startling discovery.

Julie believed she had a stalker.

For years, the 40-year-old had complained of someone harassing her. They'd call the family home and hang up. Leave pornographic photos around the family's garden, cars and garage.

It began shortly after Julie admitted to a brief affair with a co-worker years earlier.

According to Dateline, Julie believed he may have been responsible, but police were never able to identify who was behind the harassment.

Mark and Julie Jensen. Image: Dateline.

The letter.

The most chilling discovery was yet to come.

Days after Julie's death, her neighbours approached police with a letter that would change everything.

Julie said Mark was acting suspiciously, and she feared her "early demise", according to a photo of the note obtained by Dateline.

"If anything happens to me, he would be my first suspect," she wrote.

"I would never take my life because of my kids — they are everything to me!"

The letter detailed her fears that Mark was planning to kill her, making it look like suicide or an accident. She even mentioned concerns about being poisoned.

Julie and Mark had met in college, married soon after, and had two sons together. But behind closed doors, things were far from perfect.

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Julie's fears proved tragically accurate. When toxicology results came back weeks later, they revealed she had died from ethylene glycol poisoning — the main ingredient in antifreeze.

When a detective confronted Mark about the letter, he reportedly dismissed his wife as "off the wall".

Detectives knew they had their man, but proving it would be difficult.

"I never for a moment thought Julie Jensen committed suicide," former Kenosha County district attorney Robert Jambois told Dateline. "But what I did know is that the defence would be that she committed suicide."

Despite Julie saying she'd never take her own life, two days before her death she'd been prescribed antidepressants after talking to a therapist about her failing marriage.

A search of the family computer revealed Mark had been researching methods of poisoning in the weeks leading up to Julie's death.

Computer analysis also uncovered that Julie wasn't the only one who had stepped out of the relationship.

Police told Dateline there was "clear evidence" Mark was having an ongoing affair with a co-worker named Kelly LaBonte.

Just weeks after Julie's death, Kelly moved into the family home. Despite this, Mark told police she was "just a friend".

According to Mark's account to police, Julie was so sick the day of her death she couldn't get out of bed. Yet he maintained he didn't seek help, saying she had asked him not to.

Julie Jensen. Image: Dateline.

The trials.

On March 19, 2002, Mark was charged with first-degree murder.

Despite this, he posted a substantial bond and was released, allowing him to continue his life relatively normally. He started his own construction company, married Kelly LaBonte, and had another child with her.

The case took years to build. In 2006, a crucial witness came forward — a former colleague who recalled a disturbing conversation with Mark roughly a month before Julie's death, during which Mark had discussed methods of poisoning a spouse.

After a lengthy legal battle, a judge ruled that Julie's prophetic letter could be presented as evidence at trial — a decision that would prove pivotal.

Mark's first trial began in 2008. Prosecutors presented a compelling case that included not only the letter and toxicology evidence, but also testimony from jailhouse informant Aaron Dillard, who claimed Mark had confessed to killing his wife while behind bars.

After a six-week trial and more than 30 hours of jury deliberation, Mark was found guilty of his wife's murder and sentenced to life in prison.

But Mark's conviction wouldn't stand. On December 18, 2013, a federal judge overturned his murder conviction, ruling that Julie's letter should never have been allowed in court as it violated Mark's constitutional rights.

Nearly a decade later, in 2023, Mark faced trial once again. This time, prosecutors would have to build their case without Julie's prophetic letter as evidence.

According to Dateline, prosecutors used computer analysis to uncover evidence that Mark was the one making the threatening phone calls and leaving pornographic materials around their property — a calculated campaign of psychological abuse designed to make Julie appear unstable and paranoid.

Despite the absence of the letter, the jury heard enough evidence to reach the same conclusion.

Mark was convicted of first-degree murder once again and sentenced to life without parole.

Feature image: Dateline.