“Secrets in Pleasant Prairie”: Dateline Reports on Julie Jensen Homicide April 19 2025

This Saturday, April 19, 2025, Dateline NBC presents a haunting episode titled “Secrets in Pleasant Prairie,” revisiting a case that spanned more than two decades and left a permanent mark on the Wisconsin community where it began. Julie Jensen, a 40-year-old mother of two, was found dead in her Pleasant Prairie home in 1998. At first glance, her death seemed to be a suicide. But a letter she had written shortly before dying—warning that if anything happened to her, her husband should be the prime suspect—became the foundation of a lengthy and complex murder investigation.

Correspondent Andrea Canning guides viewers through the twists and turns of a case built on a document written from beyond the grave, a husband’s suspicious behavior, and relentless determination by prosecutors and Julie’s family. The episode offers interviews with investigators, prosecutors, and Julie’s loved ones, painting a full picture of the chilling betrayal and the long battle for justice.

A Marriage with Cracks Beneath the Surface

Julie and Mark Jensen met in college in the early 1980s and settled into suburban life in Pleasant Prairie, Wisconsin. They had two young sons and, from the outside, appeared to be a typical American family. Julie worked part-time, while Mark was employed as a branch manager for a financial firm. But underneath the surface, their marriage was fraying.

Julie had confided in others about her fears and suspicions. She had experienced harassment in the form of disturbing phone calls and pornography sent to the home—anonymous threats that unnerved her deeply. She had also discovered unsettling items in Mark’s planner and believed he was trying to paint her as mentally unstable. These discoveries led her to write a now-infamous letter in November 1998, which she handed to a neighbor for safekeeping. In the letter, she stated clearly that she feared for her life and that she would never take her own life, especially because of her children.

Death and the Emergence of Suspicion

On December 3, 1998, Mark Jensen called 911 to report that Julie was dead. She was found in bed, unresponsive and without visible signs of trauma. At the time, authorities considered it a possible suicide. However, investigators soon became uneasy with the circumstances. Julie had reportedly been very ill in the days prior but had been left alone by her husband. The position of her body, details about her symptoms, and Mark’s demeanor all raised red flags.

Then came the letter. When Julie’s neighbor turned it over to police, the investigation shifted dramatically. Toxicological testing revealed small amounts of ethylene glycol, the main chemical in antifreeze, in her system. Though initially overlooked, it became apparent that this may have been a slow poisoning. The letter, which seemed to predict Julie’s death and name her killer, became central to the prosecution’s theory that Mark had deliberately poisoned his wife.

The 2008 Trial and a Letter from the Grave

It wasn’t until March 2002 that Mark Jensen was officially charged with Julie’s murder. Prosecutors contended that Mark had slowly poisoned Julie using antifreeze and ultimately suffocated her when the poison did not act quickly enough. The prosecution introduced several pieces of evidence, including internet searches conducted on the morning of Julie’s death about symptoms of ethylene glycol poisoning and conversations Mark allegedly had with co-workers about ways to kill someone.

The most damning piece of evidence was the letter Julie had written. Despite legal challenges concerning hearsay and the defendant’s Sixth Amendment right to confront witnesses, the Wisconsin Supreme Court allowed the letter’s admission under the “forfeiture by wrongdoing” doctrine. In 2008, after a lengthy trial and more than 30 hours of jury deliberation, Mark Jensen was convicted of first-degree intentional homicide and sentenced to life in prison without parole.

Appeals, Overturned Verdict, and a Long Legal Battle

Mark Jensen’s conviction did not end the legal saga. In 2013, a federal judge overturned the conviction, ruling that the admission of Julie’s letter had violated Mark’s constitutional rights. This decision, later upheld by the Seventh Circuit Court of Appeals in 2015, set off a series of appeals and hearings. Prosecutors vowed to retry the case, though this time without relying on the controversial letter.

The legal wrangling dragged on for nearly a decade. In the interim, the original conviction was briefly reinstated by a state judge in 2017, only to be reversed again in 2020. Julie’s family, along with prosecutors, remained determined to bring the case to a final conclusion. New evidence and forensic technology helped strengthen the case as preparations for a retrial resumed.

The 2023 Retrial and a Renewed Conviction

Mark Jensen’s second trial began in January 2023 in Kenosha County. Without the letter, the prosecution relied on other compelling pieces of evidence. Investigators presented proof that Mark had staged the harassment Julie had experienced, including emails he sent to himself with altered sender information to appear threatening. They also reintroduced the internet searches from the morning of her death, which were conducted while Julie was reportedly too sick to leave bed.

Prosecutors also presented testimony from a former colleague and a jailhouse informant who both recounted chilling conversations with Mark about poisoning. Together, these elements painted a clear picture of premeditation. On February 1, 2023, the jury returned a guilty verdict after a single day of deliberation. Two months later, on April 14, 2023, Mark Jensen was sentenced to life in prison without the possibility of parole for a second time.

A Family’s Long Fight for Justice

Julie Jensen’s death was not just a case of domestic violence but a protracted battle for truth and justice. Her family remained steadfast over two decades, despite legal setbacks and delays. Prosecutors, particularly Bob Jambois and Angelina Gabriele, dedicated their careers to securing a conviction that would stand.

The case of Julie Jensen is both tragic and extraordinary. It highlights how persistence, evolving legal doctrine, and forensic advances can bring about justice, even after decades of uncertainty. “Secrets in Pleasant Prairie” offers a thorough account of this haunting case, reminding viewers of the consequences of manipulation, betrayal, and the importance of listening to victims—especially when they speak from beyond the grave.