The Letter

This broadcast first aired April 15, 2008. It was updated on Aug. 18, 2009.

In December 1998, police in Pleasant Prairie, Wis., were called to the Lake Shore Drive home of Mark and Julie Jensen. Inside, Mark had found his wife's body lying in her bed.

Initially, investigators thought suicide was a strong possibility. But a letter written by Julie before her death pointed police in a different direction.

Was the husband somehow involved in his wife's death, as the letter hints? Or did Julie poison herself and pen the letter to implicate Mark in a twisted plot gone wrong, as his parents allege?

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Pleasant Prairie, Wis. is about an hour north of Chicago, on the western shores of Lake Michigan. It booms in the summertime, but when the Wisconsin winter settles in, the village becomes a cold, bleak place.

No one who lived there was quite prepared for what happened on Dec. 3, 1998.

Special prosecutor Bob Jambois, who at the time was the Kenosha County district attorney, remembers, "My pager went off. I got called to the scene. They told me, 'Well, the M.E. is saying it's probably natural causes but we have some questions, so you might want to come out there.'"

Jambois had a lot of questions about what he found inside the house. "Forty-year-old women don't drop dead for no reason," he explains.

Asked if he had considered that Julie might have committed suicide, Jambois tells correspondent Erin Moriarty, "We absolutely considered that, right from the beginning."

Julie's brothers, Paul, Patrick, Mike, and Larry Griffin, were shocked by the news.

Mark also struggled to explain his wife's sudden death. "He appeared somewhat shaken. And he was rambling on about some drugs that she had taken recently, Ambien and Paxil. And talking about some kind of a drug interaction," Julie's brother Paul remembers.

"Mark was an emotional basket case. He was in tears. He could hardly stand up. He didn't know what to say or he didn't know how to talk," Mark's father, Dan Jensen, remembers.

Mark had been with Julie for 20 years, since they had been high school sweethearts. They started college together, too, but Julie dropped out just one semester short of a degree in nursing.

"She did great with all the book work and everything. She had difficulty because she got very close to the patients. And emotionally she couldn't take it," Paul explains.

What drew Julie to Mark, say her brothers, was his drive: he was a young stockbroker, and on the move.

On April 13, 1984, the night before Mark and Julie got married, Julie's mother June suddenly passed out. "Our mother collapsed at the wedding rehearsal. And we didn't know what the problem was. And as it turned out she was under alcohol withdrawal. So it was very, very disappointing for Julie," Paul explains.

"She told me her mother had ruined everything that was important to her in her life. And if she had a wedding, her mother was going to ruin that, too. And of course, she did," Mark's mother Florence tells Moriarty.

It was the first time that the Jensens realized that Julie's mother was battling alcoholism and depression.

Florence says Julie was afraid she'd end up like her mother. "As she got older, she could feel that she was becoming more like her mother and I'm sure her episodes of depression were part of that," she says.

Shortly after Mark and Julie's first child David was born in 1991, their marriage was rocked by the revelation that Julie had had an affair with another man.

Julie filed for divorce but changed her mind after she and Mark went to counseling. They had another son, Doug, in 1995, but the marriage was strained. By fall of 1998, Mark began telling friends that his wife was depressed

Julie went to see her family doctor, who prescribed an antidepressant. Two days later, she was dead.

With no obvious signs of injury and an inconclusive autopsy, the cause of Julie's death could not be determined.

Her brother Patrick says it's "not possible" that Julie had taken her own life. Julie had never talked about suicide and she didn't leave a suicide note, but, as it turns out, she did leave a letter.

In the fall of 1998, Julie blurted out an unusual story to a woman she barely knew. "She said, 'I think my husband's going to kill me.' I went 'What? That's a very serious accusation to make,'" remembers Theresa DeFazio, who was David Jensen's third grade teacher.

Julie also shared her fears with Ted and Margaret Wojt. The accusation shocked the Wojts, who had been the Jensens' next door neighbors for seven years.

Margaret says the couple had seemed "very" happy. But Ted says that in August 1998, after taking a new job, Mark seemed to change, becoming very critical of Julie. "He's telling her she's a bad mother, a bad influence on the kids," Ted says.

Two months later, Julie said Mark was acting suspiciously, searching the Web for poisons, and writing bizarre notes, which Julie photographed.

"She started saying things like, 'I found some notes next to his computer that had lists of drugs and syringes and paraphernalia that I think would be something he would use on me,'" DeFazio remembers.

By early November, the Wojts had become very concerned. "She got very sick," Ted recalls.

Asked what Julie said, Ted says, "He's trying to kill me some ways, somehow."

"My husband said, 'Take the boys, leave. You need the money, I give you money,' and she said no," Margaret adds.

And Theresa DeFazio suggested Julie go to a shelter. Again, she said no.

On Nov. 21, Julie gave Ted a letter to give to the police if anything happened to her. Ted says he didn't read the letter, and his wife says she spoke to Julie for the last time on Dec. 2.

That's when Julie called Margaret to say that she wasn't feeling well. "For some reason I didn't want to hang up. I keep asking her 'Please let me help. Let me do something,' and she keeps saying 'No,' and keeps saying, 'Mark is being good to me,' 'Mark is taking care of me.' And that was the last time I spoke with her. Her voice was shaky. Like she was drunk," Margaret remembers.

A little more than 24 hours later Julie was dead. The Wojts took her letter to the authorities.

Julie's letter referred to a photo of a list that she found - the same list she had mentioned to her son's teacher. "This list was in my husband's business daily planner not meant for me to see. I don't know what it means but if anything happens to me he would be my first suspect," Julie wrote. "I pray I'm wrong and nothing happens but I am suspicious of Mark's suspicious behaviors and fear for my early demise."

Bob Jambois says that letter reinforced his suspicions. And he grew even more suspicious when experts examined the Jensen home computer: someone had tried to erase its history, but not everything was gone.

"The computer was a treasure trove of inculpatory evidence. It really helped tell the whole story," Jambois says. "First of all it showed us the motive, because there were e-mails between Mark and Kelly. We didn't know he had a girlfriend on the side."

"Kelly," as in Kelly Labonte, is a woman Mark met at his new job, and the e-mails spelled it all out for investigators.

And that wasn't all Jambois found on the Jensen home computer: "He was looking up ways to kill his wife on the computer."

Just as Julie had reported to the Wojts, the computer's history revealed search after search for various poisons, including ethylene glycol, the main ingredient in antifreeze.

"About 50 milliliters I think coulda killed her easily. It's maybe a couple of swigs from a can of soda," says Mary Mainland, a physician who was the Kenosha County medical examiner.

Dr. Mainland says ethylene glycol has a sweet taste and is easily disguised. Most of the ethylene glycol cases Mainland investigated were in fact suicides.

But she believes this was a murder and that Julie was poisoned sometime Tuesday night, two days before she died. "Because she started to exhibit symptoms in the overnight hours," Mainland says.

But at first toxicology tests showed no sign of ethylene glycol in Julie's system.

Frustrated, investigators confronted Mark with Julie's accusing letter. Mark seemed a little stunned, but finally denied that he had anything to do with his wife's death.

Like police, Jambois believes Julie's words prove that she was murdered. "I would never take my life because of my kids they are everything to me," he reads from the letter.

But others read the same words very differently. "It's premeditated. It was planned years in advance. It was fabricated. It was crafted," says Mark's father Dan.

"She wanted the kids, the house, and everything. She wanted it all. And she didn't want a husband," Florence adds.

"The evidence is abundantly clear that Mark Jensen, in a very cold and calculated fashion, murdered his wife. You know, it's just the most cold-blooded case I've ever seen," says Bob Jambois.

It took more than two years, and three labs, but tests finally revealed a small amount of ethylene glycol in Julie's stomach. Neither Assistant District Attorney Angie Gabrielle nor Bob Jambois believe Julie had taken her own life; Jambois believes this is a poisoning murder case.

In March 2002, Mark was arrested and charged with the first-degree murder of his wife Julie.

Mark's parents believe the police have it all wrong, and that as a trained nurse, Julie knew all about drugs and poisons. Dan and Florence Jensen say that Julie, after going on the home computer to do research, took the small amount of ethylene glycol herself but never intended to die.

They believe Julie was trying to make it look as if she was being poisoned by Mark so that he would go to prison and she would end up with the kids and the house. And they think that she had miscalculated the dose and died as a result.

They also say Julie's letter was part of her plan. "It was all part and parcel of several years of her framing and planning how she was going to do this," Dan says. "She needed witnesses besides the poisons. She made sure that she gave this letter to the next door neighbor. She needed to establish people who would be witnesses on her behalf."

"The fact that Dan Jensen or Florence Jensen say they believe something, that carries no weight with me at all. They're both a couple of liars," Jambois says.

But the Jensens aren't the only ones who think Julie may have orchestrated her own death: a forensic pathologist hired by Mark's defense called the letter "contrived, unbelievable, and self-serving."

What will a jury think? They may never see the letter. By law, Mark has the right to confront his accuser in court. But Julie was dead. So before trial, Jensen's attorneys argued the letter should be thrown out as evidence. Shockingly, the judge agreed.

Jambois decided to fight for the letter. His appeal, which took another five long years, went all the way to the Wisconsin Supreme Court. "We fought hard to get this letter into evidence. By God, her word should be heard by that jury," he says.

The state Supreme Court agreed: Julie's letter could be used at trial, but only if the state could show at a preliminary hearing that there was enough other incriminating evidence to point to Mark as the killer.

It was now July 2007, almost nine years after Julie's death. Free on bail, Mark was now married to his lover, Kelly Labonte. As the hearing began, he was looking and feeling confident until, suddenly, a surprise witness took the stand.

Ed Klug, who used to work with Mark, claimed that three weeks before Julie died Mark told him he was looking up ways to kill her. "He started talking about Web sites that you could go to different poisons that would be non-detectable in a normal autopsy," Klug tells Moriarty.

Klug and Mark were in St. Louis at a company convention. They'd been drinking.

"He put a lot of thought into how he was going to get rid of her, cover it up and make it look like it was a suicide or that, you know, she was a sickly unstable woman," Klug recalls.

Asked if Mark seemed serious, Klug says, "You know, I never really saw anything in Mark that he wasn't serious."

Yet Klug never reported the conversation to the police. Why not?

"You know, at that point, I was busy, transitioning my business," he says.

"Wait a minute, though. I mean your life was busy, but well, we're talking about a possible murder," Moriarty points out.

"Right, right. You know, I guess I just didn't at that point come forward," Klug replies.

He says he didn't tell the D.A.'s office because he "was afraid to get involved."

In fact, Klug only became involved because one of his co-workers tipped off the prosecutor; Klug was then ordered to testify.

"You can't really rely on a story that comes out from drinking in the middle of the night," Dan says.

But the judge believed Klug, and raised Mark's bond to more than $1 million. Unable to pay it, Mark hugged his son goodbye and was taken to jail to await trial for murder.

Julie's brothers struggle to understand why she never shared her fears with them.

"The defense says, and will argue to this jury, that Mark didn't kill Julie at all. Julie planned this whole thing. She was going to commit suicide and punish her husband with it because he was having an affair. Isn't that a possible reason why she didn't tell any of you?" Moriarty asks.

"It's not. Julie would never, ever try to get back at her husband and leave the kids she loves with the guy she hates. It doesn't make sense," Patrick says.

But would it make sense to 12 jurors? On Jan. 3, 2008, more than nine years after Julie's death, Mark went on trial for her murder. And at the heart of the case was her letter.

Special prosecutor Bob Jambois wasted no time letting Julie "speak," by reading the letter. But Jambois also began the trial with a bombshell: he no longer believed that poison alone killed Julie.

"She was poisoned with ethylene glycol. And it may have killed her, except we now have very good reason, very good evidence that what actually killed her was Mark Jensen sitting on her and shoving her face in a pillow and suffocating her. And that's what I believe happened," Jambois said.

Julie was suffocated? Why, after more than nine years, would Jambois suddenly change his theory of how Julie died? Because of what a man named Aaron Dillard had to say.

"Mark Jensen murdered her," Dillard alleged, claiming that Mark had told him what he had done.

Just months before the trial, Dillard suddenly came forward with a shocking story: he said Mark confessed that he had killed his wife, and that at first he had tried to spike her drink with a small amount of ethylene glycol.

"So he gave her juice to drink, and that was when he told me, at that point, that it was mixed with anti-freeze," Dillard said in court.

But, according to Dillard, the poison didn't work. "He said that he got really nervous, he got scared," Dillard told the court.

Asked by Jambois if Mark had told him why he got nervous, Dillard said, "Well, she was breathing better and he didn't think she was going to die."

"And why did that scare him?" Jambois asked.

"Because the kids wanted to take her to the hospital, and if she wasn't better by the time they got home, that was where they were going to go," Dillard testified.

That's when Dillard says Mark took matters into his own hands. "He sat on her back and actually pushed on her neck into the pillow," Dillard tells Moriarty. "He said that's when she died."

Dillard's story makes sense of something that has troubled investigators all these years: the odd position of Julie's face when her body was found. "I said, 'People don't sleep like that.' I said, 'She was put in this position. Somebody put her like this,'" Jambois remembers.

The prosecution still believes that Mark poisoned his wife's drink.

In a rather startling demonstration, the Kenosha County medical examiner tasted a minute amount of ethylene glycol herself just to show the jury why Julie wouldn't have noticed she was drinking a poison.

Dr. Mainland changed her opinion on what actually killed Julie. "The cause of death is ethylene glycol poisoning with probable terminal asphyxia," she said in court.

But there was a serious problem with Aaron Dillard: he's a jailhouse snitch, with a long record of fraud. But despite the criminal convictions, Jambois says Dillard is telling the truth.

Defense attorney Craig Albee went after Dillard, who was released from jail in exchange for his testimony. "Mr. Dillard, while you were in the Kenosha County jail, you saw Mark Jensen as a way to get out of jail, right?" Albee asked.

"Yeah," Dillard acknowledged.

"And your plan to use Mark Jensen to get out of jail has worked pretty well, right?" Albee asked.

"Yes, it has," Dillard replied.

Dillard had at least four believers: Julie's brothers. "Listening to Aaron Dillard describe the cold, sickening manner in which Mark smothered her, just broke me up…. it was just very hard to listen to," says Paul.

To establish a motive for murder, the prosecution called Kelly Jensen, Mark's former mistress, and now his wife.

"As soon as he had somebody available, as soon as he had somebody on tap to replace her, bang. She was out of the picture," Jambois charged.

But the defense said the affair wasn't a motive for murder - it was the reason for suicide; it's why Julie took the ethylene glycol herself and tried to blame it on Mark.

"In your experience, someone who's concerned about being poisoned, it's very difficult to get them to drink anything?" Albee asked a defense psychiatrist.

"I've treated many paranoid patients - if she thought someone was trying to kill her, and she knew it in advance, why in the devil would she then drink it?" the psychiatrist replied.

Even Julie's own doctor said she was depressed.

And that's when another surprising witness was called: Julie's brother, Patrick. Reluctantly, Patrick admitted to the jury that at age 16, and angry at his father, he cut his wrist.

Asked if he actually intended to kill himself, Patrick tells Moriarty, "I have to say, yes, because I wouldn't hurt myself if I didn't."

"Was there a side of you concerned…that because of something you did so long ago that you could make the jury find Mark not guilty?" Moriarty asks.

"Yeah. I was very afraid of that," Patrick admits.

Mark is the only person who really knows what happened to Julie, but he decided not to take the stand in his own defense. The jury would have to rely on what he told the police nine years before.

At the time, Mark told police in a taped interview that he thought Julie had wanted to die. "She was so depressed," he told police.

In closing, special prosecutor Bob Jambois used Julie's letter to convince the jury that she was poisoned. "She wanted the world to know the truth she wanted you to know the truth. Julie Jensen had no motive to lie," Jambois told jurors in closing arguments.

The defense, meanwhile, argued that the letter was the work of a sick woman who wanted to punish her husband. "She wanted a trail left behind that pointed the finger at her husband," defense attorney Craig Albee told the jury.

Determining the truth was rougher than any juror could imagine. Eight of them and one alternate, who spoke after the verdict, say they didn't believe the prosecution's new theory that Julie was suffocated, which means they also didn't believe the prosecution's star witness, Aaron Dillard.

And even after seven weeks of trial, they still found Julie herself a mystery. "We were held up trying to determine if she had enough depression to take her own life," a juror recalls.

For three long days, the jurors were split. But then they reached a verdict, finding Mark guilty of first degree murder.

Asked what she thinks her son was feeling inside, Florence tells Moriarty, "Devastated, absolutely devastated. He knew he didn't kill her. He just thought the jury would see that, and of course they didn't."

Julie's brother Paul remembers hearing the verdict. "I was relieved. It was kinda like a big weight had been lifted off," he remembers.

In the end, Julie turned out to be the most important witness. The jury believed her letter was truly a cry for help.

Less than a week later, Mark appeared for sentencing.

"I hope the court shows the same mercy and compassion that the defendant had shown our sister Julie," Patrick said.

"I ask today for the maximum: no mercy, no parole for Mark Jensen," Paul added.

But also in court was Mark and Julie's oldest son, David, now 18. And there was another letter, this time written by David and his brother, read by the defense attorney.

"After the death of our birth mother Julie he took care of us," the letter stated. "If we ever need help advice, or just some one to talk to we know we can go to him for anything. He cares deeply for his family. In light of this, we request that our dad be eligible for parole as soon as possible. We love you dad. Thank you."

For the first time, Mark showed emotion but the judge was unmoved. Mark was sentenced to life in prison, without the possibility of parole.

Patrick created a loving tribute to his sister: an album dedicated to her life. "It's for my family to share in remembering Julie," he says. "I believe now there can be some emotional healing start to take place. And we can finally remember Julie in the pictures, who she was - a great mother, a humble, sincere person."

Jensen's second wife, Kelly, is raising their young son, as well as Julie's two children, David and Douglas. She filed for divorce in May.

Produced by Peter Henderson and Linda Martin