Deadly Exposure

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Speaker 5 She was a wife.

Speaker 6 She was a mother.

Speaker 7 She was the most amazing woman I've ever met in my life.

Speaker 5 And then suddenly, one day she was gone, poisoned by carbon monoxide.

Speaker 8 He's like, I couldn't get a pulse. I couldn't get a pulse.
I couldn't get a pulse.

Speaker 3 Her husband blamed a faulty water heater. Police blamed him.

Speaker 10 You don't think this is an accident?

Speaker 11 No.

Speaker 3 There was just one problem, and it was a big one. No one could figure out exactly how he might have done it.

Speaker 4 He's an expert in gases. He's an anesthesiologist.

Speaker 12 Did you kill your wife, Kathy?

Speaker 6 Thanks for joining us. I'm Lester Holt.
Hundreds of Americans die every year from accidental carbon monoxide poisoning. But according to police in Ohio, one of those deaths wasn't an accident.

Speaker 6 It was murder. And they say if anyone would know how to use a deadly gas to murder someone, it was their prime suspect.
Here's Kate Snow.

Speaker 17 He's come back to where it all began, to the town, the streets he knew so well, remembering the old times when life was simple, love was young, and the future held so much promise.

Speaker 23 Taking time to reflect on how it happened.

Speaker 15 A few days from now, it will all be over, one way or another.

Speaker 26 My carbon monoxide detector has gone off, and my wife's having a seizure.

Speaker 31 Our story begins in Lima, Ohio on a frantic pre-dawn morning, September 4th, 2006.

Speaker 33 Dr.

Speaker 18 Mark Wangler says he woke suddenly in the downstairs master bedroom to the sound of an alarm.

Speaker 34 What kind of alarm?

Speaker 36 Just a loud piercing noise and was able to determine that it was the carbon monoxide detector. Then I ran to check on Kathy.

Speaker 38 Kathy Wangler was 48 years old and for most of her life had suffered from epilepsy.

Speaker 18 She was sleeping upstairs.

Speaker 36 I went in and shook her and called out to her, screamed at her, but she wasn't responsive.

Speaker 36 I call 911.

Speaker 40 And you tell them that she's having a seizure.

Speaker 41 Yeah.

Speaker 27 Is she breathing? No, I think she's not breathing. Okay, sir.
I need you to check for me.

Speaker 42 No, she's not breathing.

Speaker 27 Okay, does she have a heartbeat?

Speaker 43 No, she doesn't have you.

Speaker 12 Remember doing CPR?

Speaker 36 Yes, I do remember doing the CPR.

Speaker 27 I'm sorry, CPR.

Speaker 44 Okay.

Speaker 18 Next-door neighbor, Diane Stuber, saw the rescue squad at the Wanglers' home.

Speaker 46 So I went over and I said to Mark, Mark, did she Kathy have a seizure?

Speaker 8 And he's like, I couldn't get a pulse. I couldn't get a pulse.
I couldn't get a pulse.

Speaker 10 The EMTs took Kathy to Lima Memorial Hospital.

Speaker 22 Mark followed along, and Diane Stuber was close behind.

Speaker 9 The news came in a matter of minutes.

Speaker 33 Kathy was dead of acute carbon monoxide poisoning.

Speaker 12 Do you remember when they told you that she had passed?

Speaker 41 No, I do not.

Speaker 19 Why do you think you don't remember any of that?

Speaker 36 Well, I was poisoned with carbon monoxide.

Speaker 18 It's an odorless, tasteless, colorless gas, but as a doctor, Mark Wangler says he knew he had been poisoned with carbon monoxide because his head hurt and he felt so disoriented.

Speaker 18 Neighbor Diane Stuber says she remembers how Mark took the news of Kathy's death.

Speaker 46 He sobbed like a baby. The tears were rolling down his cheeks.

Speaker 8 And he was just like, you know, this.

Speaker 46 He couldn't believe that it had happened.

Speaker 36 I wanted to see Kathy's face. I wanted to see Kathy.

Speaker 33 To say goodbye.

Speaker 2 Yeah, it was tough.

Speaker 37 Kathy's family members drove to Lima Memorial.

Speaker 50 They'd only been told there'd been some kind of accident.

Speaker 14 They found their way to a waiting room.

Speaker 52 They told us in the room, and then that was a very hard moment.

Speaker 11 It's hard to see your parents cry.

Speaker 53 And then turn around calling brothers and sisters.

Speaker 38 Mark Wangler called his two sons Nathan and Aaron who were living in Cincinnati.

Speaker 40 Aaron was in his second year of college.

Speaker 7 I just remember it just screaming and crying.

Speaker 53 It was horrible.

Speaker 31 The brothers rushed home to their father in Lima.

Speaker 7 I remember him and my brother and I just holding each other and all of us just like sobbing and crying and like his body was like shaking from crying so hard like

Speaker 28 thousands of people are accidentally poisoned with carbon monoxide every year.

Speaker 18 It usually happens when something like a space heater, a furnace, or a water heater malfunctions.

Speaker 28 Investigators wanted to find out quickly what went wrong at the Wangler home.

Speaker 23 So a detective came to speak with Mark Wangler at the hospital.

Speaker 20 Former Allen County Sheriff Sam Krish ran the detective bureau back then.

Speaker 51 He says Dr.

Speaker 20 Wangler mentioned the water heater.

Speaker 26 Dr. Wangler made a comment that they were having problems with this water heater in the past few weeks.

Speaker 26 The flame would go out occasionally and felt that that was the problem due to the carbon monoxide detectors going off.

Speaker 15 Diane Stuber remembers her husband worried about the Wangler's water heater too, saying the exhaust pipe on the roof wasn't placed there correctly.

Speaker 10 Could that have caused a backup of carbon monoxide into the house?

Speaker 46 And he told Mark, I said, that would scare me to death, Mark.

Speaker 45 It sounded like Mark Wangler was lucky to be alive.

Speaker 18 Kathy just happened to be the one sleeping upstairs that night.

Speaker 60 Mark was downstairs.

Speaker 10 It seemed like a sad but explainable accident.

Speaker 20 But as it turns out, it wasn't so simple.

Speaker 5 Coming up, growing suspicions that something was missing.

Speaker 4 We walked around the house, we looked at the water heater, we looked at the other appliances. We just couldn't find a source.

Speaker 10 For the carbon monoxide?

Speaker 4 Right, because the appliances appear to be working properly.

Speaker 5 When dateline continues.

Speaker 9 48-year-old Kathy Wangler had a personality that filled the room.

Speaker 10 Now, she was gone, killed by carbon monoxide.

Speaker 37 For her family and friends, it was a terrible loss.

Speaker 40 For her sons, Nathan and Erin, it was devastating.

Speaker 14 As Erin told us, they adored their mother.

Speaker 7 She was amazing. The most amazing woman I've ever met in my life.
Did everything for everyone, always put herself last, always put my brother and I number one priority in her life and my dad.

Speaker 18 And she certainly didn't want to be defined by her epilepsy. It started when she was a little girl, but medication seemed

Speaker 36 I grew up in a little town of Fort Recovery, Ohio.

Speaker 58 It's in about the middle of the state, down near the Ohio-Indiana border. Small town of about 1,200 people.

Speaker 12 What was that like?

Speaker 58 I enjoyed it.

Speaker 36 I really loved growing up in a small town. We played softball in the backyard and

Speaker 41 knew all your neighbors.

Speaker 36 You knew everybody in town and everybody in town knew you. My dad owned a hardware store.

Speaker 24 That's where Mark met Kathy's grandfather, a customer at the store.

Speaker 18 One day, when Mark stopped by the grandfather's house for a visit, he met Kathy.

Speaker 50 Kathy's mother remembers a couple of months later, Mark was back.

Speaker 62 The kids come in, they go, Mark's here.

Speaker 39 I go, Mark, who?

Speaker 62 And they said, Mark, that angular guy. And I said, Where's he at? And he was out.

Speaker 62 He brought his guitar and he came and sat on the back seat, back of the truck, his vehicle, and he was strumming a guitar, singing to Kathy. Serenading her? Yes.
Yes.

Speaker 47 Yeah.

Speaker 9 They started dating, and a few years later, in 1977, Mark and Kathy got married.

Speaker 18 He was 21, she was 18.

Speaker 9 They held their wedding in a Catholic church, but by then, Mark had embraced an evangelical Christian faith.

Speaker 62 They were as happy as two people I've ever seen.

Speaker 31 And it turns out the quiet young man from Fort Recovery had big ambitions.

Speaker 9 He wanted to be a doctor.

Speaker 18 Kathy worked to put Mark through med school.

Speaker 63 Things were tight.

Speaker 40 Were you happy in those years?

Speaker 36 Yes, it was. It was a good marriage.

Speaker 10 You had two boys?

Speaker 30 Correct.

Speaker 25 Nathan and Aaron were born right as Mark was beginning his practice.

Speaker 7 We were the family that you would give hugs and kisses every morning and every night before you go to bed and when you leave for school or even if you were just going out to go hang out with your friends or wherever, like we always kissed and love.

Speaker 7 We were always like a very close family.

Speaker 59 They moved to Lima in 1990 and by then the Christian faith had become very important to Mark Wangler.

Speaker 18 They joined Grace Baptist Church.

Speaker 40 What was it about this particular church that you and Kathy both thought was a right fit?

Speaker 36 Two things.

Speaker 36 One of them is we felt that the people there were friendly and the pastor was correctly preaching God's word. And the second thing is that they had a very active children's program or youth program.

Speaker 64 Mark and Kathy and the boys.

Speaker 21 At the time, Mark's medical practice was growing.

Speaker 44 Merry Christmas.

Speaker 63 After those early years of doing without, the family was now well off.

Speaker 54 They took the boys on vacations, camping, Europe.

Speaker 18 Kathy went back to school, did some substitute teaching. Life seemed to be going well for the Wanglers.

Speaker 9 Next-door neighbor Diane Stuber was fond of both Kathy and Mark.

Speaker 46 Mark was more reserved,

Speaker 46 nice man, very patient and caring person,

Speaker 46 would help you out, do anything for you.

Speaker 46 And you know, he had his little peculiar ways about him.

Speaker 46 He was a little dorky, and he looked different from other people until you get to know Mark, and he is the most wonderful person that you could ever meet. Kathy was a lot of fun to be around.

Speaker 46 She was bubbly, she had a crazy laugh,

Speaker 61 love life,

Speaker 46 just

Speaker 46 a lot of fun.

Speaker 18 But now, after 29 years of marriage, two boys, a prosperous life, Kathy Wangler's life had ended in one terrible morning.

Speaker 10 How did it happen?

Speaker 18 Mark Wangler had told investigators he thought it was probably the water heater, so they checked that out. And the Allen County prosecutor was concerned by what they didn't discover.

Speaker 18 Prosecutor Jürgen Waldick often examines the scenes of unexplained deaths in Allen County.

Speaker 4 We walked around the house, we looked at the water heater, we looked at the other appliances, the gas furnace, the gas logs, the garage, and also the bedroom where Kathleen Wangler died.

Speaker 9 They couldn't find a problem with any of the appliances.

Speaker 4 We just couldn't find a source.

Speaker 10 For the carbon monoxide.

Speaker 44 Right.

Speaker 4 Because the appliances at that point appear to be working properly.

Speaker 18 Investigators now had a mystery on their hands. They returned to the Wangler house to do some rechecking.

Speaker 10 And then in December 2006, three months after Kathy's death, Mark Wangler says investigators told him they had looked at everything.

Speaker 10 They still didn't know what had happened, he said, but they were satisfied it was an accident.

Speaker 12 They were settled.

Speaker 36 That was what I was told.

Speaker 9 Mark was slowly trying to build a new life, but some members of Kathy's family weren't ready to move on.

Speaker 60 They were still asking questions, and they thought the answers just might lie with Mark Wangler.

Speaker 5 Coming up.

Speaker 62 And I said, we have so many questions and nothing is being answered.

Speaker 5 What did Kathy's family know that made them so suspicious?

Speaker 65 She got in the car. The boys got in the car.
Mark was hanging on the side of the car and Kathy was driving away yelling at him.

Speaker 5 When Dateline continues.

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Speaker 18 Kathy Wangler's death certificate said the cause was carbon monoxide poisoning.

Speaker 63 But what was the source?

Speaker 49 By December 2006, three months after Kathy's death, that question had grown more urgent in the minds of her family members, and sister Diana wanted answers.

Speaker 65 It was kind of like the white elephant in the room.

Speaker 40 None of us really wanted to talk about it.

Speaker 65 And it, you know, the police weren't calling us.

Speaker 40 I felt as though nothing was getting done.

Speaker 10 So Diana decided she'd had enough.

Speaker 65 So I actually called mom, and she actually called the sheriff's department.

Speaker 62 And I said, we have so many questions, and nothing is being answered.

Speaker 18 But it wasn't just questions Kathy's family had.

Speaker 13 They also had suspicions about Mark because they knew something.

Speaker 18 The Wangler marriage was a disaster, and they wanted police to know the problems went back years.

Speaker 52 What Kathy had told me is basically

Speaker 2 Mark had an affair.

Speaker 40 That can't have been easy for your sister.

Speaker 68 She could never ever forgive him for that.

Speaker 18 They managed to carry on, but over the years, Kathy's family remembers simmering tensions that could erupt into open warfare.

Speaker 24 They say Mark thought Kathy gained too much weight.

Speaker 15 She wouldn't clean the house.

Speaker 18 She spent huge amounts of money.

Speaker 29 Kathy got mad at Mark a lot.

Speaker 56 Diana recalls what happened right after a big family gathering.

Speaker 40 Mark and Kathy were fighting again.

Speaker 65 She got in the car. The boys got in the car.
Mark was hanging on the side of the car, and Kathy was driving away, yelling at him.

Speaker 65 At one point, one of the boys jumped out, and there was a lot of yelling and carrying on, and then

Speaker 65 Kathy left with the boys.

Speaker 66 Mark Wangler admits things did go downhill after the boys left for college.

Speaker 10 He says Kathy would get deeply depressed.

Speaker 36 With the boys being gone, she kind of lost her purpose in life, I would say.

Speaker 19 Were you working on it?

Speaker 36 Were you trying to yeah, we were in counseling, and then she was gone.

Speaker 21 Kathy's family knew she had been sleeping upstairs while he was downstairs, but then they heard what Mark had told investigators, and a collective alarm went off.

Speaker 67 Mark said he was sleeping with a towel under the bedroom door, a fan blowing, and the bathroom window opened.

Speaker 18 That was because the toilet in the master bathroom had overflowed, and Mark said he wanted to keep the smell out of the rest of the house.

Speaker 18 Kathy's family knew about the problem with the toilet, but they figured there was a different explanation for the towel, the fan, and the open window.

Speaker 10 They believed Mark knew there was carbon monoxide in the house because he had somehow put it there, and he was protecting himself from poisoning.

Speaker 12 How did you respond to that suspicion that was placed on you?

Speaker 26 It was devastating.

Speaker 33 Five months after Kathy died, her case file landed on the desk of a veteran detective, Clyde Breitigan, since retired. What's your instinct?

Speaker 11 In reading the reports,

Speaker 11 I

Speaker 11 was sure that the water heater, the furnace, and the vent-free gas fireplace were not the source of the carbon monoxide.

Speaker 11 So then you have to think, okay, what else in that house could produce carbon monoxide? There was a generator in the garage, there was two cars in the garage, there was a snowblower in the garage.

Speaker 11 Those all produced carbon monoxide.

Speaker 18 But of course, all those things need someone to turn turn them on.

Speaker 10 You don't think this is an accident?

Speaker 64 No.

Speaker 10 Still, if it wasn't an accident, how could someone pull that off, fill an upstairs bedroom with enough carbon monoxide to kill?

Speaker 28 Detective Breitigan knew it sounded improbable, but he kept thinking about the logic of that other detective, Sherlock Holmes.

Speaker 11 It was a matter of just eliminating the impossible things.

Speaker 11 And at the end, you're stuck with the improbable.

Speaker 18 And there's another clue Breitigan and the the Allen County prosecutor couldn't ignore.

Speaker 31 Dr. Mark Wangler had a specialty.

Speaker 4 I mean, he's an expert in gases. He's an anesthesiologist.

Speaker 21 That's right.

Speaker 10 An anesthesiologist.

Speaker 20 A doctor who knows exactly how to put people to sleep.

Speaker 32 Did he use his expertise to kill his wife?

Speaker 51 In April of 2007, seven months after Kathy's death, Detective Breidigan got a search warrant for the Wangler home.

Speaker 18 He had a videotape running as officers seized a computer, papers, and Mark's journals.

Speaker 18 Detective Breitigan says the journals really caught his attention.

Speaker 11 You'd have to read the whole thing and I cannot explain that. I wish I could.
It's just

Speaker 11 he was at like the end of his rope and I think he felt trapped.

Speaker 49 But now all these months later, Mark Wangler's life was on the upswing.

Speaker 18 He had reconnected with an old friend who shared his faith, Esther Van Dyne.

Speaker 24 A romance blossomed.

Speaker 18 You ended up getting married, I think about a year after Kathy's death.

Speaker 36 14 months, correct.

Speaker 12 Some people might think that that's pretty fast.

Speaker 33 To bounce back.

Speaker 36 Yeah, we've heard that.

Speaker 21 And the wedding bells had barely stopped ringing when Detective Breitigan got a second search warrant, because by now, he had come to believe that Mark Wangler was a killer.

Speaker 18 Breitigan thought that Wangler had used an engine of some sort, a portable generator, or maybe the vehicles, to put carbon monoxide into the heating system of his home to kill his wife.

Speaker 51 The detective wanted someone to take a closer look inside the heating ducts of the Wangler home.

Speaker 11 And we went in and dismantled the ductwork and took carpet samples and the registers out of the house.

Speaker 45 Investigators found a lab that would try to determine if soot from an internal combustion engine could be found inside the heating ducts.

Speaker 18 It would be months before they got results.

Speaker 12 Did you have any idea that as you were having this busy, happy time, investigators were still trying to put a case together?

Speaker 69 We really didn't hear anything for a long time.

Speaker 44 Yeah, we didn't hear anything at all for a long time.

Speaker 33 So you plan a trip to Zambia.

Speaker 19 Why did you end up there?

Speaker 36 One of the churches in town, a good friend of mine, had gone to Zambia with several people from his church.

Speaker 37 They learned that people in Zambia were in dire need of fresh water, so Mark and Esther joined a church mission to help dig wells there.

Speaker 51 After three weeks, it was time to go home.

Speaker 33 You land in Atlanta. Yeah.
And your son calls. He said, do you know some guy named Rydigan? They were banging on the door.

Speaker 12 That's the detective.

Speaker 47 Yeah.

Speaker 31 So you knew then.

Speaker 33 So we knew then

Speaker 33 in the Atlanta airport that there must have been an indictment and they were at the door to arrest Mark.

Speaker 28 The lab results were in on that ductwork.

Speaker 4 Coming up, the prosecution's case.

Speaker 3 Motive.

Speaker 4 We have some diaries that are pretty dark and kind of lay out what the state of the marriage was.

Speaker 5 And means.

Speaker 70 Can you tell the jury what, if anything, you noticed in that particular bedroom?

Speaker 35 I observed soot-like marking on the wall directly above the register, the heat register in there.

Speaker 5 When dateline continues.

Speaker 50 On September 19, 2009, as Mark Wangler boarded a plane from Atlanta to Ohio, he knew he was about to be charged with killing his first wife three years earlier.

Speaker 36 I felt that I needed to come back and clear my name.

Speaker 18 Two days later, sheriff's deputies came to the couple's home and arrested Mark Wangler. He was charged with aggravated murder.

Speaker 32 The trial took place in March 2011 at the Allen County Courthouse.

Speaker 23 Prosecutor Jürgen Waldick didn't have fingerprints, DNA, or an eyewitness, but he believed the evidence would show that Dr.

Speaker 18 Mark Wangler killed his wife while she was sleeping using engine exhaust containing deadly carbon monoxide.

Speaker 4 I have someone who's died of carbon monoxide poisoning,

Speaker 4 really high levels, 69%.

Speaker 4 I have a defendant who has really low levels. We have no legitimate source of carbon monoxide in the home.

Speaker 4 And we have some diaries that are pretty dark and kind of lay out what the state of the marriage was.

Speaker 14 And that's where prosecutors started with the marriage, the motive.

Speaker 18 Kathy's family bolstered the argument that the marriage was a miserable one.

Speaker 10 He criticized her weight.

Speaker 46 He didn't like her hair.

Speaker 70 Did you ever hear Mark criticize Kathy on the topic of money?

Speaker 65 Yes, he didn't like her shopping.

Speaker 51 Prosecutors suggested Mark had become increasingly angry about his wife's spending. Just after Kathy died, Mark showed investigators cash, jewelry, and credit cards he found in Kathy's car.

Speaker 21 So why not divorce?

Speaker 37 Friends and family testified Kathy wouldn't leave the marriage because she was afraid Mark would cut off her money.

Speaker 25 As for Mark?

Speaker 70 The defendant was deeply obsessed with religion, and a divorce would cause him to lose his standing and reputation in the church.

Speaker 15 And if Mark and Kathy were stuck with each other and fighting all the time, his journals painted an even bleaker picture.

Speaker 20 The man who wrote them wasn't just unhappy, he was depressed and, according to prosecutors, desperate enough to kill.

Speaker 30 Detective Breitigan took the jury through each painful entry.

Speaker 64 I am tired of her lies and hiding huge amount of money from me.

Speaker 64 She turns away each time I kiss her. She continues to reject my love towards her.
I truly longed to serve Jesus, but I became weak from the wounds Satan throws at me from within my own family.

Speaker 30 Just two months before Kathy Wangler died, Mark wrote this.

Speaker 64 Thoughts of suicide are a little strong again.

Speaker 64 Satan is attacking in new way this time, using car exhaust.

Speaker 4 That's a real red flag.

Speaker 4 It tells you the state of someone's marriage, at least in our assessment, that if your marriage is so bad that you're going to kill yourself, what other things are you willing to do?

Speaker 15 And that mention of car exhaust really got their attention.

Speaker 31 One depressing entry after another, mounting evidence of a man in misery.

Speaker 10 In the eyes of prosecutors, a motive.

Speaker 40 And that 911 call raised even more suspicion as far as the prosecution was concerned.

Speaker 42 Okay, that's fine.

Speaker 27 Okay, thanks.

Speaker 43 I'm sorry, CPR.

Speaker 69 Okay.

Speaker 4 It just didn't sound like he was doing CPR on the 911 call. It sounded like the whole thing was staged.

Speaker 31 And if Dr.

Speaker 14 Mark Wangler was doing CPR, why would the fire chief find Kathy on an air mattress?

Speaker 71 For adequate compressions, it should be on a hard surface, yes.

Speaker 4 Is that pretty basic CPR stuff?

Speaker 52 Yes, that's basic CPR.

Speaker 51 But something even more important crossed the chief's mind after he found Kathy, and this was a huge red flag for prosecutors.

Speaker 10 He said Kathy's body was cold to the touch.

Speaker 29 Odd, since Mark told 911 her heart stopped beating only minutes before.

Speaker 52 We discussed with each other in the ambulance on the way to the hospital that

Speaker 52 she was cold.

Speaker 4 Which would have been unusual for someone who had just minutes before quit breathing and a heartbeat.

Speaker 71 That's crack.

Speaker 14 The ER doctor backed him up on that.

Speaker 72 She had a rectal temperature that was quite low.

Speaker 72 My documentation is that it was like 94.

Speaker 18 The doctor also testified the body seemed to be getting stiff.

Speaker 72 It seemed like she'd been dead for a while.

Speaker 63 In other words, dead before her husband called 911.

Speaker 40 There was more.

Speaker 32 The prosecution suggested Mark Wangler's grief was phony.

Speaker 4 What was his emotional state that you observed at that point?

Speaker 72 He was acting like he was crying, but I didn't really see.

Speaker 72 normal stuff when you cry, you know.

Speaker 18 In the days that followed Kathy's death, investigators tested and retested the water heater and other appliances.

Speaker 18 Prosecutors reminded the jury there was no sign any appliance had accidentally released carbon monoxide.

Speaker 10 And that was the crux of the case.

Speaker 4 It either had to be the water heater or it was murder. That's the bottom line.

Speaker 17 And if it was murder, how would he have done it?

Speaker 18 Prosecutors believe Mark Wangler closed all the heating vents except the ones in Kathy's room. Then he must have shut the doors to the furnace room, except for the one leading to the garage.

Speaker 49 He could have started a car or a generator or maybe both and filled the garage with carbon monoxide.

Speaker 9 The carbon monoxide would then find the only open path down the stairs into the furnace.

Speaker 56 The deadly gas would then travel through the heating ducts and out the vents in Kathy's room.

Speaker 22 They pointed to pictures taken of Kathy's room after she died.

Speaker 70 Can you tell the jury what, if anything, you noticed in that particular bedroom?

Speaker 53 I observed

Speaker 35 a soot-like marking on the wall directly above the register, the heat register, in there.

Speaker 23 Nobody actually tested that stain on the wall before it was painted over, but prosecutors were prepared to show that engine exhaust had come through the heating ducts and out those vents.

Speaker 9 Prosecutors now presented the key scientific evidence designed to wipe out any remaining doubt about the source of the carbon monoxide.

Speaker 18 Lab chemists had tested the inside of the heating ducts and said they indeed found soot that shouldn't have been there.

Speaker 4 Can you say to a reasonable degree of scientific certainty that the exhaust from a combustion source was directly introduced into the ventilation system? Yes.

Speaker 4 And can you say to a reasonable degree of scientific certainty that the water heater was not the source of the soot in the ventilation system?

Speaker 1 Yes.

Speaker 33 Devastating for Mark Wangler's case?

Speaker 15 Maybe.

Speaker 29 Maybe not.

Speaker 5 Coming up.

Speaker 73 Ladies and gentlemen, you will hear from our experts that this is junk science as applied to the facts of this case.

Speaker 73 You will find that there is reasonable doubt, that you may even find that the water heater did this. But regardless, you will not find that Dr.
Wangler murdered his wife, because he did not.

Speaker 5 When Digline continues.

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Speaker 12 Dr. Wangler, did you kill your wife, Kathy?

Speaker 36 Absolutely not.

Speaker 14 He had waited more than three years to defend himself.

Speaker 24 All that time, his sons stood by him and against their mother's family.

Speaker 7 When you have your family stabbing you in the back and trying to destroy your own family of what you have left,

Speaker 3 it's hard. It hurts.

Speaker 38 It was time now for the defense to present its case.

Speaker 18 Time for defense defense attorney Chris McDowell to show the jury a different version of the man who stood accused.

Speaker 55 In his opening argument, McDowell said Mark was, above all, a devoted Christian who would never commit murder.

Speaker 73 Mark did not believe that it was good enough just to profess the words of Christ or to go to church. He felt that he had to live it.

Speaker 54 Mark Wangler's defense came down to this.

Speaker 51 His wife died in a horrible accident.

Speaker 45 The prosecution never proved a crime was even committed.

Speaker 42 Ladies and gentlemen of the jury, Dr.

Speaker 73 Mark Wangler is innocent.

Speaker 73 This case has been brought as a result of a poor police investigation. An investigation, despite what you just heard from the prosecution, did not eliminate fugitive carbon monoxide as a source.

Speaker 73 from the hot water heater.

Speaker 45 The water heater was now at the heart of the Wangler defense.

Speaker 18 If the jury believed it malfunctioned that night and could have sent carbon monoxide into Kathy's room, that was reasonable doubt.

Speaker 20 Are you worried that a jury won't, in the end, believe your story? Sure.

Speaker 36 It's always a possibility.

Speaker 40 Do you think about what it would be like?

Speaker 12 You face up to the rest of your life in prison?

Speaker 36 I try not to.

Speaker 36 For the most part.

Speaker 18 Sons Aaron and Nathan provided key testimony.

Speaker 73 How would you describe your father?

Speaker 7 Say a great man.

Speaker 7 Very humble, passionate,

Speaker 7 caring, very relaxed, down to earth,

Speaker 7 very humble.

Speaker 33 Have you ever for a moment doubted your dad's innocence?

Speaker 7 Never once.

Speaker 14 Both Aaron and Nathan said they believed their parents really did love each other.

Speaker 73 Up to the day of her death, do you believe that your father loved your mother?

Speaker 52 Absolutely.

Speaker 50 And then the defense turned to the Mark Wangler journals with their depressing entries about the marriage.

Speaker 54 The defense challenged the detective.

Speaker 38 Didn't the diaries portray a man working on his marriage?

Speaker 73 Mark prays for a good relationship with his wife, correct?

Speaker 11 Yes, he does.

Speaker 73 And he prays that his wife will also sort of see the way and work on the relationship too, doesn't he?

Speaker 4 Yes.

Speaker 30 Then the forensic evidence.

Speaker 18 Prosecutors had said Kathy's low body temperature showed Mark had killed her with carbon monoxide before he called 911.

Speaker 10 But the question was, when exactly did that poisonous gas kill her?

Speaker 18 The prosecution had argued she was already dead when her husband called 911 because her body was so cold.

Speaker 10 But how cold was it?

Speaker 51 Apparently, the ER doctor got the temperature wrong.

Speaker 73 This is the nurse's handwritten notes indicating that the body temperature, the rectal temperature, is actually 1.5 degrees more than what you had written in your other notes. Is that correct?

Speaker 72 Is that, yes, ma'am? Yes, yes, I'm sorry. Okay.
Yes.

Speaker 32 So Kathy's body wasn't as cold as the doctor thought.

Speaker 48 Considering this, a leading forensic pathologist testified her heart could easily have stopped exactly when Mark Wangler said it stopped during the 911 call.

Speaker 17 The defense also had to knock down evidence from the Wisconsin lab.

Speaker 18 You remember, the lab experts said they had found soot inside the Wangler's heating ducts that came from engine exhaust.

Speaker 73 This is junk science as applied to the facts of this case.

Speaker 59 McDowell said other bigger reputable agencies like the FBI and the Ohio State Criminal Lab refused to do the testing.

Speaker 18 It was too unreliable.

Speaker 73 These people at Wisconsin said, we've never done it before,

Speaker 73 but we can try it.

Speaker 18 McDowell attacked the lab's data, its record keeping, and its expertise.

Speaker 54 Prior to your work and involvement in this case, you had no previous experience in conducting analysis on ductwork, did you?

Speaker 52 No, we've not done duct work before.

Speaker 33 And then this question, did the lab consider other sources of soot?

Speaker 73 You would agree that candles are a potential source of soot, correct?

Speaker 7 Yes, that is correct.

Speaker 56 Candles.

Speaker 18 The Wangler house was full of them.

Speaker 20 According to testimony from several witnesses, like son Aaron Wangler, maybe that's why the heating ducts were full of soot.

Speaker 64 Do you recall if your mother ever burned any candles in the home here?

Speaker 7 All the time. We had tons of candles.

Speaker 18 And remember those soot stains coming out of the registers in the room where Kathy died?

Speaker 37 That was Aaron's old room.

Speaker 7 Those marks were actually there before I moved for college. So that was back in 2004.

Speaker 18 The defense said the prosecution's murder scenario involving vehicle exhaust and the furnace was preposterous.

Speaker 48 It had to be the simple explanation.

Speaker 28 Kathy's death was an accident.

Speaker 18 And now came the most important testimony in the defense's case.

Speaker 51 An environmental toxicologist testified the most likely source of carbon monoxide was the water heater.

Speaker 73 What was the closest source of carbon monoxide?

Speaker 78 The gas-fired water heater in the basement of their home. I think, as I recall, pretty directly below her bedroom, two floors up.

Speaker 63 The water heater, he said, was a disaster waiting to happen.

Speaker 17 One code violation after another.

Speaker 78 My major concern was that

Speaker 78 this water heater wasn't in the open as most water heaters are. It was in a sealed cabinet.

Speaker 18 Closed up in that box, he said the unit could have been deprived of oxygen, creating a risk of carbon monoxide. He said venting was another problem.

Speaker 45 The vent cap was the wrong kind, and the exhaust pipe was set too low on the roof.

Speaker 18 It was all installed so poorly, he suggested, that deadly carbon monoxide could have backed up into the the home.

Speaker 15 The water heater was so faulty, said McDowell.

Speaker 73 You will hear from our experts that this is junk science as applied to the facts of this case. You will find that there is reasonable doubt, that you may even find that the water heater did this.

Speaker 73 But regardless, you will not find that Dr. Wangler murdered his wife because he did not.

Speaker 5 Coming up.

Speaker 34 You had expert testimony on both sides of this.

Speaker 44 Right.

Speaker 34 Did it come down to science for you?

Speaker 39 I don't think so.

Speaker 6 The verdict.

Speaker 57 We, the jury, being duly impaneled and sworn find the defendant, Mark A.

Speaker 26 Wangler.

Speaker 5 When dateline continues.

Speaker 37 On a cold Sunday in early March 2011, Dr.

Speaker 18 Mark Wangler, who was standing trial for murder, seemed to want a moment with those who were standing by him.

Speaker 24 During a weekend break from the trial, he showed us around his hometown, about an hour's drive from Lima, Ohio.

Speaker 21 His old house is still there.

Speaker 25 His sister and brother-in-law own the family hardware store now.

Speaker 55 It was a strange homecoming, with so much at stake.

Speaker 60 He seemed so relaxed.

Speaker 79 Yeah, I haven't worked in here since 1977, and there's some of my pruning. Yeah.

Speaker 41 Okay, enough reminiscing.

Speaker 24 Mark Wangler wanted to see his mother, a chat, and then goodbye.

Speaker 28 Was it just for now or for good?

Speaker 53 I hope this isn't the last one.

Speaker 79 I hope we get to come back easily.

Speaker 26 I'm pretty confident.

Speaker 41 I'm feeling pretty good about it.

Speaker 16 Even on this night before closing arguments, Esther and Mark held to their routine, like choir practice at Grace Baptist.

Speaker 18 Mark Wangler never testified on his own behalf.

Speaker 9 Would it matter?

Speaker 24 He was as quiet as ever and so hard to read.

Speaker 10 But not Esther.

Speaker 32 She was a wreck, wondering what will happen.

Speaker 18 What are the jurors thinking?

Speaker 24 In a courtroom back in Lima, closing arguments, where defense attorney Chris McDowell insisted the prosecution failed to make its case.

Speaker 73 Did you hear them explain to you how Dr. Wangler allegedly committed this crime? No, you didn't

Speaker 73 really hear any solid theory on that.

Speaker 10 It was an accident, he said.

Speaker 23 It was the water heater.

Speaker 73 The government has failed to disprove it as the source. As a result, there's reasonable doubt you must return a verdict of not guilty in this case.

Speaker 23 In his closing argument, prosecutor Jürgen Waldig outlined his murder scenario for the jury.

Speaker 18 The heating vents, the doors, all shut to create a direct pathway from the garage to the furnace to Kathy's room.

Speaker 1 And then

Speaker 71 he started the car

Speaker 4 or the generator or maybe both.

Speaker 52 And then he waited.

Speaker 18 And the water heater?

Speaker 63 It was checked over and over, he said.

Speaker 23 Sure, there were code violations.

Speaker 4 But you know what? That didn't kill her.

Speaker 20 And then the jury got the case.

Speaker 18 Two weeks of testimony, much of it dense and scientific.

Speaker 37 What mattered most to the jury?

Speaker 34 You had expert testimony on both sides of this.

Speaker 3 Right.

Speaker 34 did it come down to science for you?

Speaker 22 I don't think so.

Speaker 56 An afternoon passed, and by the next afternoon, their verdict was in.

Speaker 21 Esther was sitting with her son and Mark's family.

Speaker 20 Kathy's family was seated on the other side.

Speaker 57 We, the jury, being duly impaneled and sworn, find the defendant Mark A. Wangler guilty of aggravated murder.

Speaker 20 Dr. Mark Wangler was sentenced to to life in prison, eligible for parole after serving 25 years.

Speaker 26 Mr.

Speaker 57 Wangler, you violated

Speaker 26 the Ten Commandments.

Speaker 57 Thou shalt not kill.

Speaker 57 You also violated

Speaker 64 the Hippocratic Oath.

Speaker 57 As a doctor, you shall do no harm.

Speaker 19 Do you remember that moment?

Speaker 7 Yeah,

Speaker 7 I was shocked, but just beyond sad, I just bawled. I cried hysterically, and

Speaker 7 I mean thinking about it still like makes me want to cry because it's hard, you know. I'd like

Speaker 7 I only have one parent now and they took him from me, so

Speaker 7 it's hard.

Speaker 25 We spoke with jury members both on camera and off.

Speaker 66 They said it was the simpler things that convinced them.

Speaker 25 The 911 call, the diary, the body temperature, and the malfunctioning water heater, they didn't buy it.

Speaker 80 Elden and a couple of the other jurors were very knowledgeable on furnaces and hot water heaters, so they gave their opinion of how they felt that it could have happened or could not have happened.

Speaker 34 You ruled out the water heater.

Speaker 10 Pretty fast, I think within the, what, first hour or two.

Speaker 59 To this day, do you have any idea how this crime might have been committed?

Speaker 44 I don't know.

Speaker 73 No, ma'am.

Speaker 33 It was vindication for Kathy's family, especially her mother, who addressed the court.

Speaker 42 We know you have always been a very selfish person who really did not care about our beautiful daughter, only yourself. Nathan and Erin, you are our first two grandchildren.
Our family love you.

Speaker 42 We always will love you. And I hope someday we can have a connection like we had before.

Speaker 33 After his sentencing, Mark's wife Esther visited her husband in prison as much as possible. I just hope and pray that

Speaker 33 he doesn't get hurt.

Speaker 65 Or worse.

Speaker 21 Detective Bridigan says there were no winners in this case.

Speaker 18 He was only following evidence, he says, that led to a very sad conclusion about Mark Wangler.

Speaker 11 I think there was a lot of rage in him, and although he wanted to live right or he wanted to have a good marriage, I think he couldn't. So.

Speaker 40 You think he didn't see a way out?

Speaker 11 I don't think he saw a way out.

Speaker 6 That's all for now. I'm Lester Holt.
For all of us at NBC News, thanks for joining us.

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