20/20 Episode Summary: "The Kill List"

Introduction

"The Kill List," an episode of ABC News' acclaimed true crime series 20/20, delves deep into the mysterious and harrowing case of Mark Jensen, who stands accused of murdering his wife, Julie Jensen, by poisoning her with antifreeze. Released on December 28, 2024, this episode meticulously chronicles the 25-year-long legal battle, uncovering layers of marital turmoil, deceit, and relentless courtroom drama.

Background: The Jensens’ Idyllic Life

The story unfolds in Pleasant Prairie, Wisconsin, a serene lakeside community adjacent to Kenosha. Mark and Julie Jensen epitomized the American dream—an accomplished family living on Lake Michigan with two young sons, David and Douglas. Mark, a successful stockbroker following in his father Dan Jensen’s footsteps, was seen as a pillar of integrity in the community. Julie, the loving mother and homemaker, was cherished by friends and family alike for her warmth and dedication to her children.

“Julie was the only girl in a family with four boys. She just had that kind of aura about her,” Mark recounts about Julie, highlighting her pivotal role within their household and community.

Marital Struggles and Turmoil

Despite their outwardly perfect life, cracks began to appear in the Jensens' marriage. Following the birth of their first son, David, in 1990, Julie grappled with postpartum depression and felt increasingly isolated as Mark immersed himself in his career and personal pursuits. In 1991, overwhelmed by these challenges, Julie filed for divorce due to Mark’s disinterest and indulgence in drinking and partying.

“She was so embarrassed. But I thought maybe Julie’s found somebody else,” shares a close family friend, shedding light on Julie’s internal struggles and her brief affair with coworker Perry Tirica. Julie’s confession of her infidelity was met with Mark’s refusal to grant a divorce, threatening to sever his access to their children—a move that bound Julie to the marriage despite her unhappiness.

Escalating Harassment: Gaslighting or Something More?

As Julie attempted to salvage her marriage through counseling, a sinister pattern of harassment emerged. Anonymous sources began planting pornographic images of Julie around their home—on doors, sheds, and even Mark’s windshield—and making harassing phone calls. Despite reporting these incidents to the Pleasant Prairie Police Department, the frustration persisted for six years without resolution.

Detective Bob Jambois reflects on the perplexing nature of the harassment: “Someone was obviously attempting to cause some humiliation,” he notes, suspecting Mark’s possible involvement as a form of gaslighting to destabilize Julie.

Julie’s fear intensified, believing Mark was orchestrating these acts to manipulate her emotions and potentially drive her to suicide. “Mark would kill me first before he divorced me,” she confided to a neighbor, underscoring the depth of her fear.

Julie’s Death: Unraveling the Mystery

On December 3, 1998, Julie Jensen was found dead in her bedroom, exhibiting no visible signs of struggle or violence. Her body contained traces of ethylene glycol (antifreeze) and antidepressants, substances that can be lethal in specific doses. Notably, Julie was found in a peculiar position with her arm twisted beneath her, adding to the mystery surrounding her death.

“Here was apparently a healthy woman lying dead in her bed. And compounding the mystery, Julie's body is lying in a strange position,” recounts Bob Jambois, highlighting the enigmatic circumstances of her passing.

Investigation and Critical Evidence

The initial investigation lacked clear evidence of foul play, complicating the determination of Julie's cause of death. A pivotal breakthrough occurred when investigators examined the Jensen family computer—a rare household possession in 1998—and uncovered extensive internet search histories related to poisoning methods, including ethylene glycol and pipe bombs.

“Mark Jensen had spent well over a month to two months planning his wife’s murder,” Jambois asserts, emphasizing the significance of the digital evidence in unraveling the case.

Further incriminating evidence surfaced through Discovery of emails between Mark and Kelly Labonte, Mark's mistress, revealing an ongoing affair and providing a potential motive rooted in jealousy and desire for divorce.

Julie’s Last Words: The Letter from the Grave

A game-changing piece of evidence emerged in the form of a handwritten letter allegedly authored by Julie Jensen shortly before her death. The letter, titled “The Kill List,” openly accused Mark of orchestrating her demise and hinted at his capacity for manipulation and violence.

“This letter was so critical to the case that the defense fought tooth and nail to keep it out,” explains prosecutor Carla McNeil, underscoring the letter’s weight in establishing Mark’s guilt.

However, the defense challenged the admissibility of the letter, invoking the Sixth Amendment’s right to confront one’s accuser, as Julie could not testify in her defense. This legal hurdle delayed Mark's trial for nearly a decade.

Mark’s Affair and Further Complications

Throughout the investigation, Mark’s extramarital relationship with Kelly Labonte became a focal point. Their intimate exchanges, ranging from flirtatious messages to explicit plans, painted a picture of a man deeply entangled in deceit. Kelly’s testimony and the recovered emails provided clear evidence of Mark’s infidelity and his disregard for Julie’s well-being.

“Mark was looking for ways to kill her in such a way that he could get away with it,” notes Detective Ratzberg, highlighting Mark's calculated approach to committing murder while minimizing immediate suspicion.

Trial and Conviction: 2008 Verdict

In 2008, Mark Jensen faced trial for the intentional homicide of Julie. The prosecution presented the damning evidence: the harassment campaign, the poisoning intent evidenced by his computer searches, and Julie’s accusatory letter. The jury, influenced heavily by the letter’s compelling narrative, found Mark guilty of first-degree intentional homicide after a three-day deliberation.

“We the jury find the defendant, Mark D. Jensen, guilty of intentional homicide of the first degree,” the verdict was pronounced, marking a pivotal moment in the case.

Mark’s shocked demeanor contrasted sharply with his earlier composure, raising suspicions about his true feelings regarding his conviction.

Retrial and Exclusion of Crucial Evidence: 2023 Proceedings

Nearly 15 years later, in 2023, Mark Jensen returned to the Kenosha County Courthouse for a retrial after his initial conviction was overturned. The central issue revolved around the admissibility of Julie’s letter. The court ruled that the letter could not be presented to the new jury, stripping the prosecution of a vital piece of evidence that directly implicated Mark.

Despite the letter’s exclusion, other evidence persisted. Witnesses like Ed Klug, a former coworker, testified about unsettling conversations with Mark, including discussions about poisoning one’s spouse. Additionally, Aaron Dillard, another convict who had previously cooperated, recounted Mark’s admissions to poisoning Julie.

“He said, 'I'm going to have my folks take care of him,'” shares Ed Klug, revealing Mark’s chilling plans to eliminate obstacles.

Key Testimonies and Final Verdict

During the 2023 trial, testimonies from fellow inmates and witnesses like Aaron Dillard added layers to Mark’s culpability. Despite the absence of the letter, the cumulative weight of evidence, including Mark’s own incriminating internet searches and the affidavits from those who knew his disturbing plans, led the jury to deliver a guilty verdict once more.

“We the jury find the defendant, Mark D. Jensen, guilty of intentional homicide, first degree,” echoed again, affirming the prosecution’s stance despite legal challenges.

Aftermath and Continuing Appeals

Mark Jensen, now facing repeated convictions, remains steadfast in his claims of innocence, advocating for new trials and questioning the integrity of the evidence presented. Prosecutor Bob Jambois remains relentlessly committed to overturning the reluctance to convict, emphasizing the depth of his pursuit for justice.

Julie’s family, particularly her sons David and Douglas, continue to seek closure, grappling with the emotional scars left by her untimely death and the prolonged legal battles that ensued.

“Julie loved him more than anything in the world, and he murdered her so that she couldn't do that,” her brother Larry Griffin poignantly asserts, underscoring the enduring impact of Julie’s loss.

Conclusion

"The Kill List" encapsulates a tragic narrative of love, betrayal, and the quest for justice. Through exhaustive investigative reporting and compelling witness testimonies, 20/20 paints a comprehensive picture of a man’s descent into darkness and the resilience of those seeking truth. The episode not only highlights the intricacies of the legal system but also the profound personal toll such cases exact on families and communities.

Notable Quotes with Speaker Attribution

• Mark Jensen on Julie’s Aura: “Julie was the only girl in a family with four boys. She just had that kind of aura about her.” [00:05:30]

• District Attorney Bob Jambois on Harassment: “Someone was obviously attempting to cause some humiliation.” [00:12:45]

• Detective Ratzberg on Poisoning Intent: “Mark was looking for ways to kill her in such a way that he could get away with it.” [00:18:20]

• Prosecutor Carla McNeil on the Letter: “This letter was so critical to the case that the defense fought tooth and nail to keep it out.” [00:21:10]

• Ed Klug on Mark’s Threats: “He said, 'I'm going to have my folks take care of him,'” [00:29:50]

• Aaron Dillard on Mark’s Actions: “He took her to school, and then he went back home, and Julie was breathing better. So at that point, he felt nervous and figured he had to do something on his own.” [00:35:15]

• Larry Griffin on Julie’s Love: “Julie loved him more than anything in the world, and he murdered her so that she couldn't do that.” [00:42:00]

Timestamped Highlights

• 00:00 - 03:00: Introduction and initial discovery of Julie Jensen’s death.
• 03:00 - 10:00: Background on the Jensen family and marital struggles.
• 10:00 - 18:00: Emergence of harassment and Julie’s fears.
• 18:00 - 24:00: Details surrounding Julie’s death and initial investigation.
• 24:00 - 35:00: Uncovering of Mark’s affair and critical evidence.
• 35:00 - 45:00: The 2008 trial, conviction, and Mark’s initial sentencing.
• 45:00 - 60:00: The 2023 retrial without the handwritten letter and subsequent guilty verdict.
• 60:00 - End: Aftermath, continuing appeals, and reflections on the long-term impact.

Conclusion

Through "The Kill List," 20/20 offers a compelling exploration of one of Pleasant Prairie’s most baffling crimes. The episode masterfully intertwines personal testimonies, expert insights, and legal intricacies, providing viewers with a comprehensive understanding of Julie Jensen's tragic demise and the relentless pursuit of justice for her family. For those who have not listened, this summary encapsulates the essence of a case marked by deception, fear, and the enduring quest to uncover the truth.