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Murder by Antifreeze - The Chilling Death of a Wisconsin Mother · Murder Files Unsealed

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Speaker 1: Imagine a life that you know, on the surface looks
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completely idyllic, a beautiful home, loving family, quiet town. Now
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picture that perfect facade hiding something really dark, deeply unsettling.
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Today we're diving deep into Pleasant Prairie, Wisconsin, a place
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where what seemed like a tragic natural death turned out
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to be well, something much more sinister. Our mission today
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is to unpack the chilling murder of Julie Jensen by
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her husband Mark using anti freeze. And this isn't just
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a crime story. It's really complex. There's this haunting letter
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from Julie herself, legal battles stretching for decades, two big trials.
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We're going to explore everything Julie's life or death, the investigation,
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which was super intricate, the legal stuff, and what this
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whole case means. You know, in a broader sense, it's
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not just what happened, but why. It matters, how it
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reveals those hidden dangers sometimes in cities, ones within relationships.
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So let's start by setting the scene. Pleasant Prairie, Wisconsin.
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Small town seems pretty peaceful right on Lake Michigan, maybe
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forty miles south of Milwaukee. And this is where Julie
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Carrol Jensen her maiden name was Griffin, and Mark Jensen lived.
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They really projected this image of an idyllic suburban life.
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They were in the upscale Carol Beach neighborhood and for
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the outside, yeah, they looked successful. Mark was doing well
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as a stockbroker, a branch manager in or a scene.
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So financially things seemed pretty stable, comfortable.
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Speaker 2: Yeah, And what's really striking is just how well that
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image was kept up. Julie, she wasn't just uninvolved professionally
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before kids. She actually held a Series seven license that's
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for stockbrokers and had worked in that field. But then
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after their first son, David was born in nineteen ninety,
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she became a stay at home mom. Douglas, their second son,
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came along later, So to the neighbors anyone looking in,
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they just seemed like this typical American family raising their
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two boys. David was eight, Douglas just three, in this
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nice house near the lake. The whole perception was just
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normal content, But that was masking what was really going on.
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Speaker 1: Right, because that surface story it definitely wasn't the whole picture.
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And what investigators started digging into it, well, here's where
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it gets really interesting. Beneath that calm surface, their marriage
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was actually falling apart. Julie had a brief affair back
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in the early nineties with a coworker and that will
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put a huge strain on the marriage.
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Speaker 2: And after she told Mark about the affair, things got
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really bad for Julie. She started getting harassed relentlessly, anonymous
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hang up calls, finding pornographic pictures left around the house,
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on their cars, and she documented all of it, kept
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this detailed logbook because she suspected it was, you know,
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retaliation for the affair. This wasn't random. It feels very
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much like coercive control trying to destabilize her and all
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that stress, it seriously impacted her mental health. By late
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ninety eight, she was looking for help. She saw a
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doctor actually on December first, nineteen ninety eight, got prescribed
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Paxel for depression and well, the intense distress about the
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marriage falling apart, and it makes you wonder, right, how
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much did this hidden struggle, this pressure contribute to what happened.
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Speaker 3: Next, Which brings us to this really pivotal piece of evidence,
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maybe the most crucial part, a letter written by Julie
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herself just two weeks before she died in November twenty first,
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nineteen ninety eight. And this letter wasn't just you know,
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a diary entry is addressed directly to the Pleasant Puririe
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Police Department. She gave it to a neighbor to hold
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onto and the contents, yeah, just chilling. She wrote about
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being suspicious of Mark. The quote is I pray that
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I'm wrong and nothing happens, but I'm suspicious of Mark's
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suspicious behaviors and fear for my early demise.
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Speaker 2: And crucially, she makes it crystal clear in the letter
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she is not suicidal. She talks about how much she
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loves her kids, how devoted she is to them, and
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then she names Mark says he should be the first
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suspect if anything happens to her. She also included a photo.
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It was of a list she found in Mark's planner.
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What was on it wasn't totally clear then, but she
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thought it was incriminating. This letter, I mean, it became
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known as the Letter from the grave. It was the
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absolute cornerstone for the prosecution. It basically allowed Julie to
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speak from beyond to accuse him. But whether it should
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have been allowed in court that sparked years and years
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of legal fights really shaped the whole case.
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Speaker 1: Okay, so fast forward just a couple of weeks. December third,
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nineteen ninety eight. Mark Jensen calls nine to one one
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says he found Julie dead in their bed. So respinders arrive,
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They find her under the covers. I just wearing T
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shirt and underwear, no obvious signs of trauma. Mark's story
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was that she'd been sick for days, couldn't get out
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of bed, wasn't thinking clearly. And you know, the initial
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autoxy by the Kenosha County Medical Examiner, it actually came
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back inconclusive, couldn't say how or why she died.
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Speaker 2: But the district Attorney, Bob jimbois he was at the
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scene and he noticed things right away, things that fell
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off Julie's body position. For one, it seemed unnatural. Her
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arm was pinned underneath, her nose looked kind of pushed
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to one side. That detail is fascinating, isn't it? Because
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it immediately suggested maybe she hadn't died in that position,
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maybe she was moved rolled over. So yeah, suspicion pretty
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quickly fell on Mark, especially with that letter hanging out
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there on what people knew about the marriage problems. The
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investigator sees the family computer and bam, that was huge.
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They found internet searches, searches for poisoning methods, specifically queries
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about ethylene glycol anti freeze, and then further tests on
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Julie's body came back traces of ethylene glycol and her blood,
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her stomach, her urine, showing she'd ingested it not just once,
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but probably over several days. That's when the medical examiner
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changed the ruling homicide ethylene glycol poisoning and asphyxiation.
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Speaker 1: Ethylene glycol anti freeze. It's just such a disturbing choice
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for a poison odorless, apparently sweet tasting, easy to get,
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just incredibly.
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Speaker 2: Deceptive, exactly, And that's what makes it so insidious, right
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The symptoms nausea, confusion, organ failure, they're severe, but they
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can mimic so many other things. It makes it really
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hard to suspect poisoning right away. And like you said,
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initially there were no anti freeze containers found right there
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in the house when she died, which is why Jean
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Bois the DA even considered suicide at first. But Julie's
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letter explicitly saying I'm not suicidal, plus the evidence she'd
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ingested it over time that pointed straight to murder.
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Speaker 1: And then as they dug deeper, other testimonies started to surface,
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things that really strengthened the case against Mark.
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Speaker 2: Yeah, a really significant one came from a jailhouse informant,
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a guy named Dillard. He testified Mark confessed while they
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were locked up together, said Mark admitted poisoning Julie with
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anti freeze. Dillard claimed Mark told him he panicked when
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it wasn't working fast enough, so he suffocated her with
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a pillow to make sure she was dead before the
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kids got home. Then it was Ed Klugg, he was
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a colleague of Mark's club, remembered this like casual conversation
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they had after a conference where Mark supposedly talked about
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poisoning methods, even mentioned ethelene glycol. It sort of suggests
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this wasn't an impulsive thing, maybe something he'd been thinking
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about researching. And investigators also looked hard at that harassment
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campaign Julie went through. While they couldn't prove definitively in
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court that Mark was behind the calls and photos, authorready
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strongly suspected it was him, you know, maybe trying to
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break her down mentally, create this narrative that she was unstable,
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potentially suicidal. It all just added to this picture of
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him being manipulative, controlling.
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Speaker 1: So Mark Jensen gets arrested with first degree intentional homicide.
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His first trial was in two thousand and eight. They
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moved into Walworth County because of all the publicity in Kenosha.
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Yeah and yeah, it was a huge media sensation.
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Speaker 2: The prosecutor, Bob Jamboise, acting a special prosecutor, then laid
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out the case. Mark planned it, poisoned her slowly with
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anti freeze, maybe used sleeping pills too, and then suffocated her.
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And they leaned heavily on Julie's letter. It was powerful
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stuff for the jury, but the defense fought hard against
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letting it in. Argued it violated Mark's sixth Amendment right,
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you know, the right to confront your accuser, which he
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obviously couldn't do.
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Speaker 1: And the defense strategy, led by Attorney Craig Albi, was basically,
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this is a suicide. They pointed to Julie's depression, the
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marriage problems, the pack soul of the affair said she
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was deeply unhappy and took her own life. They even
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suggested maybe she framed Mark on her way out, as
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like revenge. But despite those arguments, the prosecution's evidence was
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pretty compelling. You had the computer searches, the toxicology, the
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windest testimonies. So after a long trial, six weeks and
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the jury deliberating for over thirty hours, verdict guilty first
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degree intentional homicide, sentence life in prison, no chance of parole.
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So you think, okay, case closed, just as served. But
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with this case, was it really the end?
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Speaker 2: Not even close? Mark's lawyers immediately appealed. The main point
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was that letter. They argued it should never have been admitted,
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that it violated his constitutional rights because he couldn't cross
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examine Julie. The case went all the way up Wisconsin
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Supreme Court and in twenty twenty one they actually agreed
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with the defense. They overturned the conviction granted him a
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whole new trial. The court basically said, yeah, that letter
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probably had a substantial and injurious effect on the first
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jury's decision, so they had to redo it without the letter.
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Speaker 1: Wow, So a second trial January twenty twenty three, almost
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twenty five years after Julie.
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Speaker 2: Died exactly, and this time the prosecution Angeline and Gabrielle
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was led with Jeamvois assisting they had to make their
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case without that bombshell letter, so they focused everything on
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the forensic evidence, the toxicology, the signs of asphyxiation, plus
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the witness test monies like Dillard and Clug and crucially
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those computer searches. They really hammered home how unlikely it was.
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For some absolutely criminal psychologists profilers who've looked at this case,
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they often point to behaviors consistent with narcissistic or highly
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controlling personality traits. Think about his reaction to Julie's affair
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years before, that whole harassment campaign. That suggests someone who
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needs dominance, who can't handle perceived betrayal and seeks retribution.
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It seems like it escalated, you know, from manipulation and
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psychological abuse to outright murder and the choice of weapon
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anti freeze. That says a lot too. Poisoning isn't usually
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a crime of passion, right, It's methodical, takes planning, patience, calculation.
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The computer searches prove the premeditation weeks of looking into
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ethylene glycol how to poison someone. It suggests he wanted
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to avoid immediate suspicion, make it look like she was
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sick or maybe took her own life, hoping forensic science
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wouldn't catch up.
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Speaker 1: So definitely not sudden rage. It was cold, yeah, calculated.
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And what about those hints like from Ed clar Uggs testimony.
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Does that fit the profile like he was testing the waters.
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Speaker 2: Yeah, that fits perfectly with what psychologists sometimes called rehearsal
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fantasies or testing the waters. Like you said, it's where
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someone might float an idea, maybe hypothetically to gauge reactions
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or just sort of normalize the thought in their own mind.
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And his ability to keep up appearances successful stockbroker, family
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man all while plotting this that points to a very
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compartmentalized personality. He could separate his public cell from these
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incredibly dark private intentions. That takes a certain kind of detachment.
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Speaker 1: And you mentioned earlier maybe a financial angle. He remarried
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pretty quickly to Kelly labonte Griman. Was there talk about
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life insurance or just wanting it for a start, without
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the baggage.
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Speaker 2: There wasn't direct proof of a big life insurance payout
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driving it, but the remarriage, yeah, Reais questions did he
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want a new life free from the complexities and bitterness
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of his marriage to Julie. It's plausible, so the motive
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was likely a toxic mix, you know, control, definitely, revenge
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for the affair maybe, and self preservation. Wanting to eliminate
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this person he saw as a problem, deeply personal yet
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chillingly impersonal, and how he carried it out.
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Speaker 1: And it really feels like this conviction, especially the second
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time around, without the letter hinged so much on forensic science, toxicology,
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digital evidence, oh.
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Speaker 2: Absolutely critical. Ethylene glycol poisoning, as we said, is tricky.
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Symptoms overlap with other illnesses. Back in ninety eight, forensic
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toxicology wasn't quite what it is today. That likely explains
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why the first autopsy was inconclusive. It was Julie's letter
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that really pushed them to do those specific specialized tests
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and boom, they found it, finding it in multiple places
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blood stomach urine that showed it wasn't just a one
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time accidental sip. It indicated exposure over days. Experts testified
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it was likely mixed into her food or drink, which
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points to someone in the hearsehold someone with continuous access
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like Mark, and then the asphyxiation evidenced those particular hemorrhages,
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the body position that added another layer. It painted a
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picture for the prosecution he poisoned her and when that
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wasn't working fast enough, or maybe just to be sure,
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he suffocated her. A dual mechanism. Very damning.
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Speaker 1: And the digital side too, those internet searches ethylene glycol poisoning,
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how to poison someone so incriminating, recovering those from the
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family computer, tying them to times Mark was likely using it.
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That was huge. I know the defense tried to say,
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maybe Julie did the searches planning suicide, but given the specifics,
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the timing, and her letter explicitly saying she wasn't suicidal,
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that argument didn't hold much water for the jury. That
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combination digital footprints backing up physical evidence really set a
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strong precedent thinking beyond the courtroom. This case must have
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just shaken pleasant Prairie to its core. It's not the
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kind of thing you expect in a small, quiet town.
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Speaker 2: Definitely left to Mark. It sparked really important conversations there
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about domestic abuse, about looking beyond the surface. Local groups
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actually used the case to raise awareness, you know, helping
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people recognize signs of control or manipulation that aren't always obvious.
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And Julie's letter, despite the legal battles over it, kind
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of became this symbol encouraging vic maybe to document their fears,
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to reach out even when the abuse is more psychological.
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And the impact on the kids, David and Douglas just unimaginable,
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losing their mom like that, their dad convicted of her murder,
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having to reconcile those memories. They were raised by Mark's
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second wife, Kelly, Julie's brother Larry Griffin. He's been a
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really strong voice throughout all this fighting for justice, keeping
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her memory alive and.
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Speaker 1: Legally in Wisconsin, this case had ripples too, right, the
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whole fighter with the letter and the second trial really
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showing how crucial solid forensic science is now.
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Speaker 2: Absolutely, the debate over Julie's letter definitely influenced how courts
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think about statements from victims who can't testify. It's that
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balance between getting crucial evidence and protecting the defendant's rights.
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And yeah, the second trial relying so heavily on the
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science toxicology is digital forensics. The medical Examiner's findings. It
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underscores how vital that scientific rigor is, especially in complex
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cases like poisonings. If you look at the bigger picture,
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it's just a stark reminder, isn't it, of how danger
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can hide in plain sight within families, and the challenges
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prosecutors face with tricky evidence like poisoning that can easily
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be mistaken for something else. You mentioned other cases like
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Diane Stoude, Stacy cast or other anti freeze murders. It
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does make you think about how easily accessible some really
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lethal substances are.
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Speaker 1: So wrapping this up, the Julie Jensen story is just
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this incredibly long, twenty five year journey to justice. It
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really speaks the persistence of the investigator, of the prosecutors,
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and especially Julie's family. They just never gave.
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Speaker 2: Up, and Julie herself through that letter, even with all
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the legal wrangling. It gave her a voice after death,
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a kind of agency that most victims sadly don't get.
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It shows the power of foresight, maybe an immense courage.
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Speaker 1: Her story really is a sobering reminder about domestic violence,
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how it can manifest in really insidious ways. It challenges
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all of us, I think, in our communities, to maybe
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look a little closer beyond those perfect facades, to recognize
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signs of control, manipulation, abuse that might otherwise go unnoticed.
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Urges us to think about those silent struggles.
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Speaker 2: And as Mark Jensen serves his sentence Julie's legacy, it
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does endure her story, her bravery in writing that letter,
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that justice finally achieved. It ensures her death wasn't just
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another statistic. It reminds us that even when things seem
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incredibly dark, truth can eventually come to light, often because
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people just refuse to stop looking for it.