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By Chris Hansen Correspondent
NBC News
updated 4/22/2007 7:02:33 PM ET 2007-04-22T23:02:33

This report first aired January 2, 2007, and repeats April 22, Sunday, 7 p.m.

NORTHERN MICHIGAN— lovely and unspoiled with tiny towns on crystal lakes is a tourist paradise.  Beautiful clear days give way to dark, dark nights.

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Nights that hold a multitude of secrets, some of them bone-chilling. 

Mark and Florence Unger loved the lake country.  It was a favorite getaway for them and their children—perfect, really, until it became forever the place of unspeakable tragedy.

Mark first met Florence — Flo for short — in college.

Connie Wolberg, Mark Unger's sister: She was beautiful and she was charming. And she was fun.

Mark’s sister Connie Wolberg describes Mark as a gentle teddy bear.  He and Flo began dating after graduation and married a few years later.

Wolberg: They seemed very, very much in love.

Mark was a sportscaster at a local radio station, and Flo worked in retail.

Mark Unger: I had the greatest job in the world. I went to every game.  I mean it was amazing.  And she worked at places where she could buy clothes and jewelry and stuff.  I mean, we were very happy.

Along came two beautiful boys. 

Unger: I knew she’d be an awesome mother.  And she was. 

The family bought the house in a pricey suburb of Detroit and Flo became a stay-at-home mom. To support their new lifestyle, Mark left his dream job in radio to work as a mortgage broker.  But things started to fall apart around 1998.   Mark hurt his back and became hooked on Vicodin.  He says addictions to alcohol and gambling followed... and took a big toll at home.

Unger: It was not only the Vicodin and the gambling, it was my behavior in general.  You know?  The selfishness. 

In time, Mark stopped working. The couple began sleeping in separate bedrooms.  With debts piling up, Flo reluctantly went back to work. 

In September 2002, Mark checked into rehab.  He returned home, he says clean, more than 5 months later.  By now the marriage was in shambles.

Unger: I mean she was not happy.  And she wasn’t afraid to show that.

Chris Hansen, Dateline correspondent: But was there a time when she made it clear to you that reconciliation was not on the table?

Unger: Yeah it was in a therapy appointment with our marriage counselor.

Hansen: And what did she say exactly?

Unger: Well, I don’t want to tell you exactly what she said.  That’s between—you know, us.  But that’s where it happened.  And it was painful to hear.

But friends say Mark kept hoping he and Flo would stay together. In late October, they did something they often did. Took the boys on a  trip to northern Michigan to the secluded cottages on lower herring lake at a resort called Watervale.  Flo told friends she had misgivings about making the trip. 

Unger: I’m sure she had reservations about going.  I had reservations about going.  You know?  But we we’re dedicated to those kids.

Mark says things seemed fine once they got in the car...the family listened to music and laughed for much of the four-hour drive.

Unger: The colors were pretty to look at on the way up.  The kids were having a ball. It couldn’t have been better.

After dinner at a local restaurant, they went back to their cottage.  The boys settled in to watch a movie, and Mark says he and Flo went down to this boat deck. They chatted briefly with a man who took a small boat across the lake... then Mark says he left Flo to go put the boys to bed.

Unger: Flo was very comfortable on that deck.  She wasn’t ready to come in yet I guess.

Maggie and Linn Duncan are part owners at Watervale.  They had been out to dinner that night with friends and returned around 9:30.

Linn Duncan, part-owner at Watervale: Boy it was dark I’ll tell 'ya.  That I remember. 

Mark says he spent about 15 minutes with the boys and when he went back to the boat deck, Flo was gone.   He says he saw a light on at the Duncan’s house, and figured she was there and might want privacy... he didn’t look.

Unger: It wasn’t anything earth shattering that made me not go up there.  I just  thought about it and I said, “Oh she’s up there.  She’s fine.”  And I just went back to the cottage.

When Mark woke the next morning and Flo was still missing, he called the Duncans.

Linn Duncan: It sounded like—somebody—in tears and says, “This is Mark and—my wife hasn’t come home all night.”

The Duncans went down to the boat deck -  and what they found there still haunts them.  There was Flo, face down in the shallow water.

Linn Duncan: We have memories there that’ll never disappear.  Never.

Maggie Duncan: I’ll carry it to my grave.

Maggie called 911.

911 TAPE

Operator: Benzie county 911.

Maggie Duncan: Yeah, I’m pretty upset.

Operator: Okay, what’s your name?

Maggie Duncan: Maggie Duncan.  D-u-n-c-a-n. I believe there is a suicide or a drowning or something.

While Maggie was on the phone, Linn went to get Mark.  They met between Mark’s cottage and the boat deck.  Linn says he remembers exactly what he said. 

Linn Duncan: "Mark she’s in the water.  You’re not gonna like it."

Linn says Mark made a bee-line to Flo’s body. 

Unger: I picked her up.  And put my arms underneath her.  And just lifted her up.  And there was blood just started coming out.  And I just freaked. And I just dropped her. I mean I’m in the water with my wife who’s just cold and bloody. Dead.

Hansen: And you have your children.

Unger: Yeah I wasn’t thinking.  My whole life just ended right then.  I wasn’t thinking about anything.  My whole world had ended right there.

Troy Packard was the first officer at the scene.  He sensed something was off the minute he looked over the boat deck railing.   

911 TAPE

Troy Packard:  Better call out the troops on this one.

Operator:  Oh, yeah?

Packard:  Yeah, I got blood and ...

Operator:  Oh, Jesus, are you kidding?

Packard:  There is blood on the cement platform and now she is in the water.

Packard:  So how did the blood get on the cement platform before she got in the water you know?

That question would be asked again and again in the days... weeks... and months to come.  How did blood get on the cement platform if Flo was found in the water?

In Northern Michigan,  “Up north” as they say here, crime is rare and murder rarer still.

On a clear October morning three years ago, deputy Troy Packard responded to a 911 call to Watervale. He was apprehensive.

Troy Packard, police officer:  Well, all that’s reported to me is there’s a body in the water.  You’re thinking, “Was it an accident?” “Was it a suicide?”  You know, “Was it a murder?”

Investigators took hours to comb the scene, starting with the boathouse.  On the wooden upper deck, a post was broken. 12 feet below on the concrete platform was a bloodstain.  Below that, in shallow water, was Flo’s body.

Packard says Mark Unger seemed evasive.

Packard: He just kept on saying, “I don’t know.”  And I asked him, “Well when was the last time you seen Florence alive?”  “I don’t know.” 

Packard watched Mark make a series of cell phone calls.  He was frequently interrupted by call waiting.

Packard: He would click over.  He would answer it and then

He would start trying to cry and moan and “She’s gone.  I can’t believe it,” in this great emotion. And then he’d go back to the other person and then he was all calm and fine again. It just didn’t seem right.

And something kept bothering Linn Duncan. He says he hadn’t told Mark where Flo’s body was -- how did Mark know to run to that very spot?

Linn Duncan: He jumped in the water right next to her.  And at that moment I looked around and I said to myself. “My God he did it.” 

By nightfall, Mark was under a cloud of suspicion, and Flo’s parents were given temporary custody of the boys. 

Flo was buried a few days later. Hundreds of people attended her funeral.

Months passed. The investigation seemed stalled and Mark was not charged with a crime.   He fought bitterly to regain custody of his sons, Max, age 10, and Tyler, 7.  Flo’s parents fought back. 

Claire Stern, Florence's mother: This is not about custody of the children. This is about a murder investigation. FINISH the murder investigation.

Within days of Flo’s death, Mark hired a heavy-hitting defense attorney, Bob Harrison.  Harrison has handled over 100 murder cases.

Bob Harrison, defense attorney: I had a client in a world of trouble. 

Hansen: When somebody hires Bob Harrison in a case like this what does he get?

Harrison: Well, whether it’s gonna be good enough or not you’ll get everything I’ve got.

Calling Flo’s death a tragic accident, Mark took - and passed - a lie detector test, given by a respected retired police polygrapher.

Hansen: Did you personally kill your wife Flo?

Unger: No.

But prosecutors didn’t buy it. In May of 2004, seven months after their trip to Watervale, Mark was charged with the premeditated murder of his wife.

Hansen: In Michigan when you’re convicted of first degree murder you have to face a mandatory life sentence.

Harrison: Correct.

Hansen: No parole here.

Harrison: Until you die.

Attorney Donna Pendergast led the prosecution. Daughter of a Detroit cop, Pendergast has been called Michigan’s best prosecutor. This was her 93rd murder case. 

Hansen: How many have you won?

Donna Pendergast, prosecutor: All but two.

Hansen: That’s a pretty good record.

Pendergast: Uhm, I’ve been lucky.

This time Pendergast had her work cut out for her. She had a tough opponent and a weak case.

Hansen: There was no DNA evidence.

Pendergast:  No.

Hansen: No fingerprints.

Pendergast: No. But we had circumstantial evidence. And we believed with what was admissible as evidence, that we could present a pretty clear picture for the jury.

And so began a trial that would last nearly nine weeks and would include mountains of conflicting evidence. Detailed pathology reports, a recreation of Mark’s walk down to the water that morning,  a wooden mock-up of the deck railing, and explicit animations—all of it leading to very different conclusions. 

The biggest trial this small community ever witnessed began with an extraordinary field trip to the scene. With the defendant’s mother, the defendant himself, the twelve people charged with his fate, and the victim’s father all mingled where Flo died. 

Prosecutors painted this picture of what happened that night. They claimed Mark and Flo argued on the boathouse deck, that Mark pushed Flo and that she fell 12 feet onto the cement below.  She was unconscious but alive. Mark left her there and went back into the cottage to tuck his children into bed— and this, prosecutors said, is why her murder was premeditated. Mark waited over an hour before he returned to the deck and killed Flo by pulling her into the water where she drowned.

Back in the courtroom, Donna Pendergast began building her case by asking witnesses there that day to describe Mark'sodd demeanor.

Pendergast (in court): So you indicated he had kind of going between crying and matter of fact?

Tom Kelley: Yeah.  And I’d offer him Kleenexes and he’d take them, but I never saw a tear. 

Fran D'Angela: He got noticeably upset sobbing very loudly, but I never noticed any tears. 

And deputy Packard told the jury he was stunned to find that just hours after the discovery of Flo'sbody, Mark had already packed up the family car. 

Packard said Mark kept repeating, “I just want to leave.”

Deputy Troy Packard: I found it peculiar because that’s all he was saying.  He just wanted to leave.  And here’s Florence, still lying face down in the water.

But Pendergast was not going to convict Mark Unger on peculiar behavior alone. She planned to make her case around a marriage in trouble and something about Flo that made it very unlikely for her to have stayed out on that boat deck alone.

Hansen: And what was your theme in this case?

Donna Pendergast: Well, in this case it was pretty clear—that this woman was not just scared, but terrified of the dark. And the bottom line is, if you believed that she truly was afraid of the dark, then she simply would not have stayed out on the deck where it’s pitch-black. Then his story failed from the get-go.

The prosecution team of Donna Pendergast, Mark Bilkovic and John Skrynzski pieced together a timeline for the jury of the weeks leading up to Flo’s death. By mid-October, 2003, the Unger divorce proceedings had gotten very ugly. 

Amy Folbe (in court): Mark told her that he was going to get custody of the children, he was going to get the house.  She would get no child support and little alimony.

Amy Folbe: She felt very threatened.

Peter Stern: She told me that she would live in a box before she let the kids go.

Steve Frank: She said, you know, “I don’t want to have to do it but if he tries to take the kids from me and the house I’m going to have to get nasty about the divorce.”

And she did lash back at Mark — in a divorce hearing on Tuesday, October 21st, four days before she died. There Flo insisted she would fight hard to keep the boys — though Mark had begged her not to — she demanded the release of all the records of Mark’s gambling debts and drug addictions. The battle spilled over at home. Flo told friends it was the worst week of her life.

Susan Witus: She said, “I don’t want to talk about it in detail, but I was very upset.”  And “I’ve been crying on the bathroom floor for the last two nights.”                  

Bilkovic: Did she ever use the term warring with you?     

Witus: She said they’ve been, that, yeah, that they’d been warring all week.

Glenn Stark: She said Mark had become increasingly erratic.  And, uh, unpredictable, withdrawn.

Flo told this man, Glenn Stark, that she had spent hours that week locked in the bathroom, crying.

Bilkovic: Did she ever characterize or give a nickname or a paraphrase to the type of behavior that she indicated the defendant was exhibiting?

Glenn Stark: Yes.  She said he was exhibiting Dr. Jekyll and Mr. Hyde behavior.       

Prosecutors had another reason for putting stark on the stand. His relationship with Flo hinted at a motive for murder.

Bilkovic: Now you and Florence Unger had a very close friendship, is that fair to say?

Stark: Yes.

Bilkovic: And did that friendship ever turn physical?

Stark: Yes, it did.

Stark testified that he and Flo had a secret affair and had sex a few times over a two year period, the last time just a week before her death. 

Mark Unger described Stark as his best friend. In fact, Stark was an overnight guest in the Unger home the night of the divorce hearing.  There is no evidence Mark knew about the affair, but Stark said he seemed distant and hostile.

Stark: I asked Mark if he was uncomfortable with me being there and if he’d preferred that I stayed somewhere else.     

Stark: He replied that, no, he wasn’t angry with me being there, I wasn’t the one who was divorcing him.

The next day, Wednesday, a neighbor encountered Flo kneeling in her garden crying.

Ronald Loeb, neighbor: I said “Hi, Flo, how are you,” and she looked up at me and she was crying, and she said “Not very well.” She told me that they were going  up north.  And that she did not want to go.  And that she was afraid to go.

But on Friday, Flo and Mark took the boys on the long drive up north to Watervale.  After dinner, the boys settled in to watch a movie, Flo and Mark went down to the boat deck. 

There they had a conversation with this man. He told jurors it was pitch black out and he told the Ungers he was about to take his boat across the lake.

Fred Oeflein: And she said, “Oh, I could never do that because I’m afraid of the dark.”

Donna Pendergast, prosecutor: So in this brief conversation you had with the Ungers she made that fear known to you?

Oeflein: Yes.

And that point was critical to the prosecution’s case — that Flo was so afraid of the dark she never would have stayed out on the boat deck alone. 

Kathy Stark: She was afraid of the dark.   

Ronald Loeb: She was very afraid of the dark.

Flo’s father said she’d been afraid for as long as he could remember.

Harold Stern, Flo's father: When she was a little child—she said, “Hold me, Daddy.  I’m scared of the dark.”  And now, 30 years later, she’s put in a place where she’s gonna be in the dark forever.

A frightened woman, an escalating custody fight... tears and betrayal. Prosecutors told the jury the pressure boiled over out here on this deck. The Ungers argued. Maybe Mark snapped, pushed Flo and then returned to the cottage.  But all of that was circumstantial—some of it pure speculation, proving the next part of the prosecution’s case was crucial: that Flo didn’t die from an accidental fall, Mark had to have pulled her from the cement into the water, where she drowned.

“The only way the injury like that can occur is the result of blunt force...”

“Looking down on the spinal cord, which we had to cut off, to remove the brain.” 

Prosecutors called on a series of forensic experts and prepared jurors to get familiar with the fine print in Flo’s autopsy report.

Donna Pendergast: In this case, it is like CSI.  In this case, the body tells the story.

The doctor who performed Flo’s autopsy catalogued her many bruises—her broken hip, internal injuries, fractured skull.  He said she became unconscious the second she hit the concrete.

Dr. Cohle: I have a hard time understanding how she got into the water.              

This controversial neuropathologist was emphatic that Flo was immobile on the cement and was placed in the water, where she drowned.

John Skrzynski, prosecutor: Now, Doctor, based on these injuries and based on the physical condition that Mrs. Unger would have been in as a result of the injuries, would she have been capable of getting into the water on her own?

Dr. LJ Dragovic: No, sir.

Skrzynski: In your opinion what was the state of her consciousness when she first went into the water?

Dr. LJ Dragovic: She didn’t go into the water.  Being unconscious, she could have only been placed into the water.

And this doctor, Paul McKeever of the University of Michigan, looked at samples of Flo’s brain tissue. He performed several tests — and said one showed proof of a brain injury that could only have appeared if Flo had been alive on the cement a very long time.

Dr. Paul McKeever: An hour-and-a-half. She would have been alive for an hour-and-a-half.

And that was the crux of the prosecution’s medical case.

Donna Pendergast: And if she was not capable of getting into the water on her own power, then somebody put her into the water.  And they had a long time to think about it before they did it.

Your honor, at this time, the people would call Linn Duncan to the stand.

The prosecution wrapped up its case by returning to Linn Duncan’s doubt — how had Mark known to run right to the body in the water.

Pendergast: Had you told or given the defendant any information whatsoever about where Florence’s body was?

Linn Duncan: No, none.

As its final piece of evidence the prosecution presented this... a videotape recreation of Mark’s route down to the water that October morning made to show he could not have seen where Flo’s body was and so could not have run right to it unless he knew it was there.

Video: Unger's route The last image was an inflatable female dummy used in CPR training, facedown in the water. 

Dramatic yes, and to some, deeply disturbing. The prosecution rested hoping it would all add up to pre-mediated murder.

Chris Hansen, Dateline correspondent: Was there reasonable doubt in this case?

Bob Harrison, defense attorney: There was so much reasonable doubt you you could climb on it.  You could walk on it.  You could throw it.  If this case didn’t contain reasonable doubt the concept does not exist.

Defense attorney Bob Harrison painted a very different picture of what happened that night on the boat deck - Mark loved Flo and had no reason to kill her. Her death was simply a tragic accident.

As for the prosecution’s theme that Flo was afraid of the dark - nonsense.

Bob Harrison: Did you have any knowledge or awareness that Florence Unger had a fear of the dark?

Lyle Wolberg: I was not aware of any...

Lori Silverstein: I do not know...

This cousin of Mark’s testified that if Flo was afraid of the dark, she didn’t show it at Watervale.

Harrison: To your knowledge, was Florence Unger ever on that boathouse deck at night when it was dark?

Marcy Zussman: Yes, she was. 

According to the defense, Mark simply left Flo for a few minutes to put the boys to bed.  During that time, she somehow tumbled off the deck and into the water.   When Mark came back and didn’t see her, he assumed she was at the neighbors and went to bed.

Harrison: At the very beginning of this investigation, a very, very sad thing happened.

Mark did not take the stand. Harrison told jurors police botched the investigation, starting when resort owner Maggie Duncan called 911. She mentioned suicide. The dispatcher passed it along to the officer sent to the scene.

Harrison said the officers got caught up looking into suicide and missed the real evidence pointing to an accident.

The defense dismissed the notion that there was anything sinister about Mark running to the spot Flo lay dead. Of course Mark ran right there, said Harrison, the boat deck was the last place he had seen her and he had just watched Linn Duncan walk up from that exact spot.

Harrison: And so after you spoke with Mark, he ran back exactly the way you had come, down to the front of the boathouse.

Linn Duncan, witness: Yes, exactly.

Harrison: Exact path practically that you had just traveled.

Duncan: Yes.

The defense argued that Mark’s mood swings while on the phone and packing the car to go home could all be explained as a natural reaction to shock and grief, and his overwhelming concern for his two young sons. 

Harrison: Didn’t he say, “I just want to take my boys.  I want to take my boys and take them home.  I just want to go home.”

Deputy Troy Packard, police officer: Yes.  He did say that.

In his cross examination of Flo’s illicit lover, Glenn Stark...

Harrison: Did you have sex in the Unger home?            

Glenn Stark: No.

Harrison seemed to be reminding the jury that Flo herself was not perfect.

Harrison: Did you go somewhere and have sex?             

Stark:   Yes.

Harrison: Do you know where Mark was at the time that you took his wife to have sex with her?    

Stark:  I do not.

Chris Hansen, Dateline correspondent: Glenn Stark...how do you describe him?

Mark Unger: My best friend was f**king my wife.  How else do you describe him?  That’s how I describe him.  The man who was bedding my wife.

Hansen: Did you—

Unger: The guy who was patting me on the back saying, “You can get through this.  You can do this.”  And he was sleeping with my wife.

Hansen: Did you know this before ...

Unger: Oh, I had no idea.  No idea.  Her best friends didn’t know about the affair, you know, so what, she’s going to all of a sudden tell me. No - Flo would have never done that.

Mark Unger insists he didn’t learn about the affair until months after Flo’s death, during pre-trial hearings.  It could not have been a motive for killing his wife, he says, if he didn’t know about it.  But the defense still had to deal with the prosecutions’ medical case, and the one piece of evidence that wasn’t circumstantial - the bloodstain on the cement.

Defense Attorney Tom McGuire scored a big point for Mark'steam when he got the doctor who did Flo’s autopsy to admit the medical evidence didn’t necessarily point to murder.

Defense Attorney Tom McGuire:  You don’t know whether this women’s death was accidental or intentional?                                

Dr. Stephen Cohle: I don’t know for sure, that’s correct.

McGuire attacked the credibility of the controversial neuropathologist who’s adamant testimony, that Flo was pulled into the water where she drowned, was so crucial to the prosecution.  

McGuire: Would it be fair to say that you like cases that generate a lot of publicity?                             

Dr. LJ Dragovic: No.                                            

McGuire: You gravitate toward cases that where you can get your name in the newspaper?                              

Dr. LJ Dragovic:  No. I, uh...

McGuire: Get your face before the cameras? Is that a fair statement, sir?              

DR. LJ Dragovic: No, sir.                                     

Several months earlier, in this hearing, the neuropathologist testified Flo was on the cement apron for only a few minutes.  But at the trial, he testified she lay there, unconscious for more than one and a half hours. 

Tom McGuire: Now, which is true, doctor?  The evidence that you gave in January, or the evidence that you gave from that witness stand, both of them were under oath, which statements are true? 

Dr. LJ Dragovic: Both of them are true.    

Tom McGuire: Both of them are true?        

Dr. LJ Dragovic: Because—of course.     

Tom McGuire: Of course? Are you just making this up as you go Dr. Dragovic? 

DR. LJ Dragovic: No, sir.     

McGuire: There is a man on trial for murder here, do you understand that, sir?

DR. LJ Dragovic: I perfectly understand that, sir.      

And the defense team had its own dramatic exhibits to unveil, including a mock up of the boat deck brought to court to show that what happened at Watervale was linked directly to the condition of the deck itself.

McGuire:  We do have a mock-up of the deck to show the jury...

Experts testified the railing was almost a foot too short to meet Michigan building code and Flo could have lost her balance.  Even the owners of Watervale admitted the deck was in bad shape.

Harrison, defense attorney (in court): In fact, in your words, the deck had gotten pretty ratty?

Linn Duncan:  (long pause) Yes.

Ratty, and, according to engineers, rotting.

David Ruby, engineer: And in the condition that the timber was it was an accident waiting to happen.

The defense team’s final witness, Dr. Igor Paul, was a mechanical engineer from MIT, produced several animations which he said explain how easily Flo could have toppled over and ended up in the water. 

Video: Defense scenario 1

Dr. Paul narrates his video: When she bounces with her head and her shoulder, her pelvis is still above her.  So that when she bounces, she actually gets propelled up in this frame. And then she continues rolling because she still has rolling energy. 

As for the blood stain on the cement...

Dr. Paul narrates his video: When she hits right now, she will be hitting with her right side of her head above her ear essentially and the blood squirts out of her nose.

A weak railing, too low to meet code, a woman who tumbled - hitting her head on concrete before rolling into the lake. An accident?

The jury was about to decide.

Prosecutor Donna Pendergast’s closing argument in Michigan v. Unger was a marathon  — the longest she’d ever given — nearly three hours. 

Donna Pendergast (prosecution closing arguments): The unfortunate truth is that a human life has been ruthlessly and recklessly obliterated.  And there will never be enough justice for that.  Never.

Defense attorney Bob Harrison went even longer, calling the accusations against Mark Unger disgraceful. 

Bob Harrison (defense closing argument): He came back and he kissed his sons again after just destroying their mother.  Hannibal Lecter in “Silence of the Lambs” couldn’t even do that. It is outrageous to suggest that anybody could destroy the life of the mother of these children and act like that.  It’s outrageous and absurd, and it’s a lie.

And so began an agonizing wait. 

For the jurors too it was agonizing, the case was full of contradictions.

Chris Hansen, Dateline Correspondent: This was not a smoking gun case.  There was no DNA evidence linking Mark Unger to the crime, no fingerprints, no eye-witnesses. Did that make it hard for you?

James, juror: Very.

Becky, juror: Yes.

Lucy, juror:  Yes.

5 members of the 12 person jury spoke with "Dateline" —a waitress, the owner of a construction company, a nurse, a pharmacy technician and a factory worker. On the first day of deliberations, they took a vote. 

Tina, juror:  I was undecided. 

Tina, juror:  It wasn’t so much doubt, as I just was not ready to commit to anything.  I really wanted to go through all of my notes.  I wanted to consider everything.

And consider they did.  25 long hours, stretched over four days.

Hansen: How did you feel as the deliberations went on?  Day one, two, three. 

Mark Unger: I was, it was just hard enough to get through those days.  Was I anticipating not guilty?  Yes.  Was I optimistic about being home that next weekend?  Absolutely.

Mid-way through the fourth day of deliberations came word a verdict had been reached.

Judge Batzer: So we’ll have the bailiff bring in the jury.

For the jurors, it was a moment of dread. 

James, juror: I didn’t want to make eye contact with the defense, the prosecution, their families.  It was—we knew it was gonna be hard.

Clerk (reading verdict): People of the State of Michigan versus Mark Steven Unger. We the jury find the defendant guilty of murder in the first degree.

Flo’s mother collapsed.

Mark’s mother and sister watched, speechless, as he was taken away in handcuffs.

These jurors say deciding Mark Unger’s fate was one of the hardest things they’ve ever done. 

Lucy, juror: We gave Mark 110 percent.  We really did. 

Hansen: He’s told that Flo is, essentially, in the water.  But apparently, not exactly where, yet he is able to go directly to the location of the body.  Suspicious?

James, juror: Very.

Suspicious too they say were Mark’s mood swings on the phone. The fact that he started packing the car to leave and didn’t pull Flo out of the lake.

Hansen: Did it bother you that he left the body in the water?

David, juror: It did.  If it was my wife laying there, I’d be doing everything I could to get her out.

And the jurors believed the theme hammered home by the prosecution.

Hansen: So you believe the fact that she was afraid of the dark?

James, juror: Yes. (they nod)

Becky, juror: And I think someone who’s not even afraid of the dark wouldn’t logically stay out there in the dark.  It’s just—it’s really dark.

Tina, juror: It just doesn’t add up.  I don’t understand why she wouldn’t go with him to put the kids to bed.

Most convincing though was the testimony about Flo’s brain injuries and the test done by this University of Michigan doctor.

Hansen: Was there one star witness in your mind?  One person who’s ... really sewed it up for you?

Becky, juror: Dr. McKeever for me. He had proof.  Concrete proof that she was alive for some period of time before she was in the water.

Once the jurors accepted that Flo had been alive on the pavement for an hour and a half, they say the defense team’s computer animations made no sense. 

David, juror: The animated picture showed that ... hit the ground, rolled over several times—had a seizure, drowned; many things, instantly.  And it just was too hard to believe.

Lucy, juror: Bodies don’t bounce, I don’t care what they say, on cement. 

So in the end, it all came back to the blood stain that caught the trooper off guard.

Hansen: If Flo’s body had been found on the cement and not in the water, do you think you would’ve had to go with this being an accident?

Tina, juror: Yes.

James, juror: I believe so, yes.

Mark’s mother had sat through nearly nine weeks of the trial and sold her house to pay for her only son’s defense.

Bette, Mark’s mother: My son is innocent, he would never hurt anyone.  I think the world knows that... except for those people.

And Flo’s mother spoke to reporters...

Reporter:  What was the first thing that went through your mind when you heard them say... 

Claire Stern, Flo's mother:  Thank you God, Justice is served.

Our interview with Mark took place two weeks later in the Benzie county jail. 

Chris Hansen, Dateline correspondent: How does a guy who’s married, two great kids.  Living in—one of the most desirable suburbs of Detroit, end up in your situation?

Mark Unger: I wish I knew.  It was a shock.  A surprise.  Every step of the way.

Now facing a life behind bars, Mark is adamant he has no idea what happened that dark October night three years ago.

Hansen: Did you kill your wife Flo?

Unger: I would never, ever hurt Flo.

Hansen: Did you kill her?

Unger: I would never do anything to hurt her.

The Unger boys are with Flo’s parents, who are planning to adopt them. Mark’s mother is suing them for more visitation.  Mark says he is heartbroken the boys are growing up without him.

Hansen: What are you going to say to them to explain what has happened here?

Unger: Just not having contact with them and—and—and you saying, you know, you will be able to.  That gives me so much hope, I can’t even tell you. And I know my boys and they know that I would never hurt their mother...

Bob Harrison calls Mark’s conviction a horrendous miscarriage of justice.

Hansen: Did you take this as a personal defeat?

Bob Harrison, defense attorney: You always do.  You can’t help it.  You are in a war of sorts with the other side and it hurts. 

Hansen: Is an innocent man now in jail?

Harrison: Absolutely.

But to the prosecution and Flo’s family, justice was served.

Donna Pendergast, prosecutor:  If you have time and you make a conscious decision to end somebody’s life, as I believed Mr. Unger did in this case, then that’s a crime, that’s not an accident.

Crystal clear days still give way to dark, dark nights...in Northern Michigan. Donna Pendergast, now 91 wins 2 losses, says her victory is Flo’s victory, and it’s bittersweet.

Pendergast: To have a wonderful mother just cut down in the prime of her life.  All murders are terrible, but this one just yanked a few strings in my heart.

Hansen: Were you the voice of Flo?

Pendergast: I like to think I was. 

Since we spoke with Mark Unger, he has lost his parental rights.

© 2013 NBCNews.com  Reprints

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