Not long before she died, 40-year-old mother of two Julie Jensen wrote a haunting letter. 

The note, intended for police and entrusted to a neighbor for safekeeping, foresaw the Wisconsin mom’s “early demise” and identified the man whom police should consider Julie’s “first suspect” in the event of her death, as reported in Dateline: Secrets Uncovered’s latest episode, “Secrets in Pleasant Prairie.”

But even with the letter in hand, it would take years — and two trials — for authorities to get justice for Julie. 

The day Julie Jensen was found dead

The 40-year-old was found dead in her bed by her husband Mark on the afternoon of December 3, 1998. 

Bob Jambois, the Kenosha County District Attorney at the time, rushed to the scene.

He noted the unusual position of Julie’s body — with her arm spread out underneath her body — and a nose that looked smashed to one side, but there was no obvious trauma or cause of death.

Mark told police that Julie hadn’t been feeling well for a few days before her death and that she was also struggling with depression. She’d gone to the doctor and was prescribed the antidepressant drug Paxil just days earlier.

With little else to go on, authorities performed a full search of the house and seized the family’s home desktop computer. 

Who Was Relentlessly Sexually Harassing Julie Jensen via Email?

Julie Jenson had reported harassment to police 

Julie was no stranger to members of the Pleasant Prairie Police Department. For years before her death, she’d been harassed by someone who would call the family’s home and hang up. Pornographic photos were also placed around the family’s yard, cars and garage, and Mark said some were placed on his car while it was parked outside his job. 

The harassment began after Julie admitted to a brief fling with a co-worker years earlier, but that man had later moved to North Carolina and police were never able to identify the person responsible for the harassment. 

After her death, police looked into Julie’s affair partner, but were quickly able to clear him in her death. 

During the analysis of the family’s computer, investigators learned that Julie wasn’t the only one to have stepped out of the marriage. According to Jambois, there was “clear evidence” that Mark was having an ongoing affair with a co-worker named Kelly LaBonte.

Just weeks after Julie’s death, LaBonte moved into the family’s home. During a police interview four months after his wife was murdered, Mark insisted that LaBonte was “just a friend.” 

During the same interview, Mark told detectives that on the morning of his wife’s death, Julie “wasn’t looking good” and had “no motor control.” He said that he never called for help, claiming that she had asked him not to.

“I just watched it happen,” he said of her deteriorating condition.

A letter from Julie Jensen from the grave

Detectives also presented Mark with a letter that Julie had written shortly before her death, identifying her husband as her “first suspect” if anything should ever happen to her. Julie wrote the note after finding a strange shopping list in Mark’s datebook for items like “drug supply,” “razors,” and a “syringe.” 

“I pray I’m wrong & nothing happens… but I am suspicious of Mark’s suspicious behaviors & fear for my early demise,” she wrote. 

The letter was a bombshell, but Jambois also knew it would be difficult to get it admitted in court since, under the law, Mark’s team should have an opportunity to cross-examine anyone who presents evidence against him.

Mark Jensen arrested for his wife’s murder 

Mark was arrested for first-degree murder, but posted a half-million dollar bond in cash and resumed life as usual, starting his own construction company, marrying LaBonte, and having another child.

Then in 2006, one of Mark’s former co-workers, Ed Klug, came forward with a shocking story about a conversation he had with Mark over drinks just weeks before Julie’s death. Klug said that Mark had admitted he hated his wife and could kill her. 

Also, after a years-long battle, a judge agreed to let Julie’s letter be presented at trial. 

Mark went on trial in 2008. Along with presenting the existing evidence against him — including those suspicious computer searches, his affair, and Julie’s letter — prosecutors also called jailhouse informant Aaron Dillard to the stand.

Jailhouse informant says Mark Jensen confessed to killing his wife

Dillard told the jury that Mark had confessed behind bars to killing his wife. He claimed that Mark told him he’d poisoned Julie with antifreeze, and that on the morning of her death, her sons were concerned about her health and wanted him to call an ambulance. 

Dillard said that Mark told his sons that he’d call for help if their mom wasn’t better by the time they got home from school. Dillard testified that with the clock now running, a panicked Mark shoved his wife’s face into a pillow to finish the job before his sons returned home.

Mark was convicted and sentenced to life in prison, but years later, an appellate court would rule that Julie’s letter never should have been admitted in court, and Mark was granted a new trial.

He went on trial for a second time in 2023. This time, although Julie’s letter was not allowed in court, prosecutors called a computer expert who testified that Mark had been the one harassing his wife with those pornographic images for years to punish her for her affair.

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