>> as for his mansion, he told us the renovations were nearly finished. a grand home for his family, that no longer exists. >> the passion in this project began with family, the late wife who found the place, hannah thought she would have a lovely live with her baby, in the garage apartment. and now they are both gone. >> but, i will finish the house, like i promised. >> at the end of the day, he says, no lavish home, no amount of money can take away the pain of losing his only daughter. on. >> hello i'm andrea canning and this is dateline. >> she was a wife, she was a

mother. >> she was the most amazing woman i had ever met in my life. >> and then, suddenly, one day, she was gone poisoned by carbon monoxide. >> he was like i couldn't get a pulse, i couldn't get a pulse. >> her husband blamed of faulty water heater, police blamed him. >> you don't think this is an accident? >> no. >> there was one problem, and it was a big one, no one could figure out exactly how he might have done it. >> he's an expert in gases, he's analyses urologist. >> murder or an accident. did you kill your wife? ♪ ♪ ♪ >> hello, and welcome to dateline, 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, it was murder, and

they say if anyone would know how to use a deadly gas to murder someone, it was their prime suspects. here is kate snow with deadly exposure. >> reporter: 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 a future held a lot of promise. taking time to reflect on how it happened. a few days from now it will all be over, one way or another. >> carbon monoxide detector is going on, my wife is having a seizure. >> our story begins in lima, ohio, on a frantic morning, september 4th, 2006. dr. wangler said he will suddenly in the downstairs master bedroom to the sound of

an alarm. what kind of alarm? >> just a loud piercing noise and i was able to determine it was the carbon monoxide detector, and i ran to check on kathy. >> kathy was 48 years old, and for most of her life suffered from epilepsy. she was sleeping upstairs. >> i went in and shook her and called out to her, screamed at her but she wasn't responsive. >> i called 9-1-1 -- >> you tell them she's having a seizure? >> yes. >> is she breathing? >> no, i think she's not breathing. >> okay, sir, i need you to check for me. >> no, she's not breathing. >> does she have a heartbeat? >> no! >> do you remember doing cpr? >> i remember doing cpr. >> i'm starting cpr. >> okay. >> next door neighbor, saw the rescue squad -- >> so i went over and said to,

mark, the jealousy share? and he said i couldn't get a pulse, i couldn't get a pulse! >> the emts took kathy to lima memorial hospital, mark followed along and diane stuver was close behind. the news came in a matter of minutes, kathy was dead of acute carbon monoxide poisoning. do you remember when they told you that she had passed? >> no, i do not. >> why do you think you don't remember any of that? >> i was poisoned with carbon monoxide. >> reporter: it's an odor-less, colorless gas, but as a doctor, mark wangler said he knew he had been poisoned with carbon monoxide because his head hurt and he felt so disoriented. neighbor diane said she remembers how mark took the news of kathy's death. >> he sobbed like a baby, the tears were rolling down his cheeks and he was like i can't believe it happened.

>> i wanted to see kathy's face, i wanted to see kathy. >> to say goodbye? >> yes, it was tough. >> kathy's family members drove to lie memorial, they had only been told there was some kind of accident, they found their way to a waiting room. >> they told us in the room, and i was a hard moment, it's hard to see your parents cry. >> and then to call your brothers and your sisters. >> mark called his two sons nathan and aaron who were living in cincinnati, aaron was in his second year of college. >> i remember screaming and crying, it was horrible. the brothers rushed home to their father in lima. >> i remember that we were just sobbing and crying, his body was shaking from crying so hard. >> thousands of people are accidentally poisoned with

carbon monoxide every year, it usually happens when something like a space heater, a furnace or water heater malfunctions, investigators wanted to find out quickly what went wrong at the wangler home, former county sheriff ran the detective bureau back then, he said wangler mentioned the water heater. >> he made a comment that they were having problem with the water heater, and in the past few weeks, the flame would go out occasionally. it felt like it was a problem due to the carbon monoxide detector going off. >> diane remembers her husband worried about the wangler water heater to saying the exhaust pipe on the roof was in place there correctly could that have caused a backup of carbon monoxide into the house? >> he told mark that would scare me to death, it sounded like mark was lucky to be alive, kathy happened to be the

one sleeping upstairs that night, mark was downstairs, it seemed like a sad but explainable accident. but as it turns out, it wasn't so simple. coming up -- growing suspicions that something was missing. >> we walk around the house, go to the water heater, the other appliances, and we couldn't find a source. >> for the carbon monoxide? >> right, the appliances seem to be working properly. >> when dateline continues. wor >> when dateline continues. icy hot.

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>> welcome back to dateline, kathy wangler was found dead in her home, the cause? carbon monoxide poisoning. it seemed like an open and shut case, an accidental death. kathy's husband mark told police they had a faulty water heater, but police weren't convinced he was telling all he knew. once again, here's kate snow with deadly exposure. >> reporter: 48-year-old kathy wangler had a personality that filled the room, now she was gone. killed by carbon monoxide, for her family and friends, it was a terrible loss, for her sons, nathan and aaron, it was devastating. as aaron told us, they adored their mother. >> she was amazing. the most amazing woman i ever

met in my life. she did everything for everyone. always put herself last. always put my brother and at number one priority and her life, and my dad. >> reporter: she certainly didn't want to be defined by her epilepsy, it started when she was a little girl but medication seem to keep it under control for the most part. kathy was 15 when she met mark wangler. >> grew up in an old town, in ohio. it's the middle of the state, near the ohio indiana border. a small town of 1200 people. >> what was that like? >> i enjoyed it, i loved growing up in a small town. we played softball in the backyard, you knew all your neighbors, everybody in town, everybody in town knew you. my dad owned a hardware store. >> reporter: that's where mark met kathy's grandfather, one day when mark stop by the grandfather's house for a visit he met kathy. kathy's mother remembers a couple of months later mark was back. >> the kids come in and say marcus here.

i say markou? and they say mark wangler. i said we is he out? and he had a guitar and he was strumming his guitar, singing to kathy. >> reporter: serenading her? >> yes. >> reporter: they started dating, and a few years later in 1977, mark and kathy got married, he was 21, she was 18. they held their wedding in a catholic church but by then, market embrace the neven jellicoe christian faith. >> they were happy as two people i had ever seen. >> reporter: it turns out the quite young man from fourth recovery had big ambitions. he wanted to be a doctor, kathy worked to put mark through medical school, things were tight. were you happy? >> yes, i definitely was. >> reporter: you had two boys? >> correct. >> reporter: nathan and aaron were born right as mark was

beginning his practice. >> we wore the family that would do hugs and kisses before bed, or before school, or if you were going out to hang out with your friends, we always kissed and hugged, we were always a close family. >> reporter: they moved to lima in 1990, and by then, the christian faith had become very important to mark wrangler. they joined race baptist church. what was it about this particular church that you and kathy both awe was a right fit? >> two things. it felt like the people there were friendly. the pastor was correctly preaching god's word. the second thing is that they had a very active children's program, youth program. >> mark, kathy and the boys -- >> marks medical practice was growing. >> merry christmas! >> reporter: after the early years of doing without, the family was now well off. they took the boys on vacations, camping, europe. kathy went back to school, did

some substitute teaching. life seemed to be going well for the wangler's. next door neighbor dianne was fond of both kathy and mark. >> mark was more reserved. nice man, very patient, caring person. would help you out, do anything for you. and, you know, he had his peculiar ways about him. 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, she was bubbly, had a crazy laugh, loved life. just a lot of fun. >> reporter: but now, after 29 years of marriage, two boys, a prosperous life, kathy wangler's life had ended in one terrible morning. how did it happen? mark wangler had told investigators he thought it was

probably the water heater. so they check that out, and the allen county prosecutor was concerned by what they didn't discover. prosecutor often examines the scenes of unexplained deaths and allen county. >> we walked in the house, look at the water heater, other blinds, gas, furnace, gas logs. the garage, and also the bedroom where kathleen wangler died. >> reporter: they couldn't find a problem with any of the appliances. >> we couldn't find a source -- >> for the carbon monoxide? >> right, because the appliances at that point appear to be working properly. >> reporter: investigators now had a mystery on their hands. they returned to the wangler house to do some rechecking. and then, in december 2006, three months after kathy's death, mark wangler said investigators told him they had looked at everything. they still didn't know what had happened, they said, but we're satisfied it was an accident.

they were settled. mark was slowly trying to build a new life, but some members of kathy's family weren't ready to move on. they were still asking questions, and they thought the answers just might lie with mark wangler. coming up -- >> i said we have so many questions, and nothing is being answered. >> reporter: what the kathy's family know that made them so suspicious? she got in the car, the boys got into the car, mark was hanging on the side of the car and kathleen was driving away, yelling at him. >> reporter: when dateline continues. him. >> reporter: when dateline continues.

>> reporter: kathy wangler's death certificate said the cause was carbon monoxide poisoning, well what was the source? by december 2006, two months after kathleen's death, the question had grown more urgent in the minds of her family members, and sister diana wanted answers. >> it was like the white elephant in the room, none of us really wanted to talk about it. and, you know, the police weren't calling us, i felt as though nothing was getting done. >> reporter: diana decided she had enough. >> i actually called mom and she actually called the sheriff's department. >> i said we have so many questions, and nothing is being

answered. >> reporter: but it wasn't just questions kathy's family had, they also had suspicions about mark. because they knew something the wangler marriage was a disaster, and they wanted police to know the problems went back years. >> kathy told me that mark had an affair. >> reporter: that couldn't have been easy for your sister? >> she couldn't forgive him for that. >> reporter: they carried on, but over the years kathy's family remembers simmering tensions that could erupt into open warfare. they say mark thought kathy gained too much weight, she wouldn't clean the house, she spend huge amounts of money. kathy got mad at mark a lot. diana recalls what happened right after they took the family portrait, mark and kathy were fighting, again. >> she got in the car, the boys got into the car, mark was hanging on the side of the car, and kathy was driving away yelling at him. at one point, one of the boys

jumped out and there was a lot of yelling and carrying on, and then, kathy left with the boys. >> reporter: mark wangler admits things did go downhill after the boys left for college. he says kathy would get deeply depressed. >> the boys being gone, she lost her purpose in life, i would say. >> reporter: were you working on it? were you trying -- >> we were in counseling. >> reporter: and then, she was gone. kathy's family knew she had been sleeping upstairs while he was downstairs, but then they heard what market told investigators, and a collective alarm went off. mark said he was sleeping with a towel under the bedroom door, a fan blowing and the bathroom window open, that was because the toilet in the master bathroom hide overflowed and mark said he wanted to keep the smell out of the rest of the house. kathy's family knew about the problem with the toilet, but they figured there was a different explanation for the towel, the fan in the open window.

they believed mark knew there was carbon monoxide in the house because he had somehow put it there, and he was protecting himself from poison. >> how did you respond to that suspicion that was placed on you? >> i was devastated. >> reporter: five months after kathy died, her case file landed on the desk of a veteran detective. what is your instinct? >> in reading the reports, i was sure that the water heater, the furnace and the vent free gas carbon -- were not a source. so what else in that house could produce carbon monoxide? there was a generator in the garage, two cars in the garage, a snow blower in the garage. those all produce carbon monoxide. >> reporter: of course, all those things need someone to turn them on. you don't think this is an accident? >> no. >> reporter: still, if it wasn't an accident, how could someone pull that off? fill an upstairs bedroom with

enough carbon monoxide to kill? detective breitigan knew it sounded improbable but he kept thinking about the logic of that other detective, sherlock homes. >> it was a matter of eliminating the impossible things and at the end you're stuck with the improbable. >> reporter: and there's another q breitigan and the allen county prosecutor couldn't ignore, dr. mark wangler had another specialty. >> he's an expert in gases, he's an anesthesiologist. >> reporter: that's right, an anesthesiologist, a doctor who knows exactly how to put people to sleep. did he use his expertise to kill his wife? in april of 2007, seven months after kathy's death, detective breitigan got a search warrant for the wangler home. he had a videotape running as officers seized a computer, papers and mark's journals. detective breitigan says the journals really caught his attention. >> you would have to read the

whole thing, and i cannot explain, i wish i could, it's just he was at the end of his rope. he felt trap. >> reporter: but now, all these months later mark wangler's life was on the upswing, he had reconnected with an old friend who shared his faith, esther vandyne. a romance blossomed. you ended up getting married, i think about a year after kathy's death. >> 14 months, correct. >> reporter: some people might think that is pretty fast to bounce back. >> we've heard that. >> reporter: 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. right again 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. the detective wanted someone to take a closer look inside the

heating ducts of the wangler home. >> we went in and dismantled the ductwork and took carpet samples and the registers out of the house. >> reporter: investigators found a lab that would try to determine if soot from an internal combustion in engine could be found inside the heating ducts, it would be months after they found results. did you have any idea, as you are having the busy, happy time, investigators were still trying to put a case together? >> we didn't hear for a long time. >> we didn't hear anything for a long time. >> reporter: you plan a trip to zambia, why did you end up there? >> one of the churches in town, a good friend of mine had gone to zambia with people from his church. >> reporter: they learned that people from zambia were in dire need of freshwater, so mark and esther joined a church mission to help dig wells there. after three weeks, it was time to go home. you land in atlanta, and your

son calls -- >> he says do you know some guy named breitigan, they are banging on the door. >> reporter: that's a detective? >> yes. >> reporter: you knew then? >> we knew then, in the atlanta airport that there must have been an indictment and they were at the door to arrest mark. >> reporter: the lab results were in on that dock work. coming up -- the prosecution's case? motive. >> we have some diaries that are pretty dark, and they show the state of the marriage. >> anything you noticed in that particular bathroom? >> i saw such markings above the wall, above the heat register. >> reporter: when dateline continues. register. >> reporter: when dateline continues. ergen-c crystals pop and fizz when you throw them back. and who doesn't love a good throwback? ( ♪♪ ) ( ♪♪ ) emergen-c crystals. go to 1-800flowers.com, find

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official contest in the democratic presidential race. the president touted his projected wins in south carolina which he is credited for turning the tide in 2020, has now put him on a path towards victory this year. officials at least 46 people were killed by forest fires in chile with a number expected to rise in the coming days the fires breaking out during a heat wave that has affected south american countries, now back to the line. ected south american countries, now back to the line. >> welcome back, i'm andrea canning, kathy wangler died of carbon monoxide poisoning in her ohio home, three years later investigators believe they had enough evidence to prove that her death was not an accident, but planned by her husband of 29 years. here again is kate snow with

deadly exposure. >> reporter: on september 19th 2009, as mark wangler boarded the plane from atlanta to ohio, he knew he was about to be charged with killing his first wife three years earlier. >> i felt that i needed to come back and clear my name. >> reporter: two days later, sheriff deputies came to the couple's home and arrested mark wangler. he was charged with aggravated murder, the trial took place in march 2011 at the allen county courthouse, prosecutor -- didn't have print fingerprints, dna or an eyewitness but he believes that the evidence would show that dr. mark wangler killed his wife while she was sleeping, using engine exhaust containing deadly carbon monoxide. >> i doubt of someone -- 16%, i have a defendant who has low levels. we have no legitimate source of carbon monoxide in the home, and we have some diaries that

are pretty dark and lay out what the state of the marriage was. >> reporter: that's when prosecutors started with the marriage, the motive. kathy's family, bolstered the argument that the marriage was a miserable one. >> he criticized her weight, he didn't like her hair. >> did you ever hear mark criticize kathy on the topic of money? >> yes, he didn't like her shopping. >> reporter: prosecutors suggested that mark had become angry about his wife spending, just after kathy died mark should investigators this cash, jewelry and credit card he found in kathy's car. so, why not divorce? friends and family testify kathy wouldn't leave the marriage because she was afraid mark would cut off her money. as for mark? >> the defendant was deeply obsessed with religion and a divorce would cause him to lose his standing and reputation in the church. >> reporter: and if mark and kathy were stuck with each other and fighting all the time, his journals painted an even bleaker picture.

the man who wrote them wasn't just unhappy, he was depressed. and according to prosecutors, desperate enough to kill. detective breitigan took the jury through each painful entry. >> i'm tired of her lies, and hiding huge amounts of money from me. she turns away every time i kiss her. she continues to reject my love towards her. i long to serve jesus, but i became weak from the wounds second through at me from within my own family. >> reporter: two months before kathy wangler died mark wrote this. >> thoughts of suicide are a little strong again, satan is attacking in new ways this time, using car exhaust. >> that's a red flag, tells you the state of the marriage, and in our assessment that if your marriage is so bad that you're willing to kill yourself, what other things are you willing to do? >> reporter: that mention of car exhaust, really got their attention. one depressing entry after

another, mounting evidence of a man in misery, in the eyes of prosecutors, a motive. and that 9-1-1 call raised even more suspicion as far as the prosecution was concerned. >> i'm still here sir. that's fine. >> i'm starting cpr. >> okay. >> it didn't sound like he was doing cpr on the 9-1-1 call. it sounded like the whole thing was staged. >> reporter: and if dr. mark wangler was doing cpr, why would the fire chief find kathy on an air mattress? >> for adequate compressions, it should be on a hard surface, yes. >> is that pretty basic cpr stuff? >> yes, that's basic cpr. >> reporter: something even more important crossed the chief's mind after he found kathy, and this was a huge red flag for prosecutors. he said kathy's body was cold to the touch. odd since mark told 9-1-1 her heart stopped beating only

minutes before. >> we discussed with each other in the ambulance on the way to the hospital that she was cold. >> which would've been unusual for someone who had just minutes before quick breathing, and had a heartbeat? >> that's correct. >> reporter: the e.r. doctor backed him up on that. >> she had a rectal temperature that was low. my documentation is that it was 94. >> reporter: the doctor also testified the bodies seem to be getting stiff. >> it seemed like she had been dead for a while. >> reporter: in other words, dead before her husband called 9-1-1. there was more. the prosecution suggested mark wangler's grief was phony. >> what was his emotional state that you observed at that point? >> he was acting like he was crying, but i didn't really see normal stuff when you cry. you know? >> in the days that followed kathy's death, investigators tested and retested the water heater and other blind says.

prosecutors reminded the jury that there is no sign any appliance had accidentally released carbon monoxide. and that was the crux of the case. >> it had to be the water heater, or it was murder. that's the bottom line. >> reporter: and if it was murder, how would he have done it? prosecutors believed mark wangler closed all the heating fence except the one in kathy's room. then he must've shut the doors to the furnace room except for the one leading to the garage. he could've started a car or a generator or maybe both, and filled with the garage with carbon monoxide, the carbon monoxide would then find the only open path, down the stairs, into the furnace. the deadly gas would then travel through the heating ducts and out the vents in kathy's room. they pointed to pictures taken of kathy's room after she died. >> can you tell the jury what if anything you notice in that particular bedroom? >> i observed a soot-like marking on the wall, directly

above the register, the heat register. >> reporter: 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. prosecutors now presented the key scientific evidence designed to wipe out any remaining doubt about the source of the carbon monoxide. lab chemists had tested the inside of the heating ducts and said that they indeed found soot that shouldn't have been there. >> 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. >> 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? >> yes. >> reporter: devastating for mark wangler's case? maybe. maybe not. did a faulty water heater cause kathy wangler's death? or was the prosecution's case

hot air? coming up -- >> ladies and gentlemen, you will hear from our expert that this is junk science, that applies to this case. you will find that there is reasonable doubt. 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. >> reporter: when dateline continues. did not. >> reporter: when dateline continues. 2 diabetes? discover the ozempic® tri-zone. ♪ ♪ i got the power of 3. i lowered my a1c, cv risk, and lost some weight. in studies, the majority of people reached an a1c under 7 and maintained it. i'm under 7. ozempic® lowers the risk of major cardiovascular events such as stroke, heart attack, or death in adults also with known heart disease. i'm lowering my risk. adults lost up to 14 pounds. i lost some weight. ozempic® isn't for people with type 1 diabetes. don't share needles or pens, or reuse needles. don't take ozempic® if you or your family ever had medullary thyroid cancer, or have multiple endocrine neoplasia syndrome type 2,

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>> absolutely not. >> he had waited more than three years to defend himself, all that time his sons stood by him, and against their mother's family. >> when you have your family stabbing you in the back and trying to destroy your own family what you have left that's hard that hurts. >> it was time now for the defense to present its case, time for defense attorney chris mcdowell to show the jury a different version of the man who stood accused. in his opening argument mcdowell said, mark was, above all a devoted christian, who would never commit murder. >> 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 limit. >> mark winkler's defense came down to this. his wife died in a horrible accident. the prosecution never proved the crime was even committed. >> ladies and gentlemen of the

jury, doctor mark wang alert is innocent. this case has been brought as a result of poor police investigation. an investigation despite what you just heard from the prosecution, did not eliminate fugitive carbon monoxide as a source from the hot water heater. >> the water heater was now at the heart of the wagner defense. if the jury believed it malfunctioned that night and could've sent carbon monoxide into kathy's room, that was reasonable doubt. >> are you worried that a jury won't, in the end believe your story? >> sure. there's always a possibility. >> do you think about what it would be like. you face up to the rest of your life in prison. >> i try not to. for the most part. >> sons erin and nathan, provided key testimony. >> how would you describe your father? >> he was a great, man very humble, passionate, caring,

very relaxed, down to earth, very humble. >> have you ever for a moment doubted your dad's innocence? >> never once. >> both erin and nathan said they believed their parents really did love each other. >> up to the day of her death do you believe that your father loved your mother? >> absolutely. >> and, then the defense turned to the mark when angler journals. with their depressing entries about the marriage. the defense challenged the defective. didn't the diaries portray a man working on his marriage? >> mark, praise for a good relationship with his wife correct? >> yes he does. >> and he praised that his wife will also, see a way to work on the relationship to doesn't? >> yes. >> then the forensic evidence. prosecutors had said kathy's low body temperature showed mark had killed her with carbon monoxide before he called 9-1- 1. but the question was.

when exactly did that poisonous gas kill her? the prosecution had argued she was already dead when her husband called 9-1-1. because her body was so cold. but how cold was it? apparently the e.r. doctor got the temperature wrong. >> this is the nurses handwritten notes, indicating that the body temperature was actually 1.5 degrees more than what you had written in your other notes. is that correct? >> yes. >> so cathy's body was not as cold as the doctor thought. considering this. a leading forensic pathologist testified her heart could easily have stopped exactly when mark wenger said it stopped. during the 9-1-1 call. the defense also had to knock down evidence from the wisconsin lab. you remember the lab experts said they had found soot inside the wenger's heating doubts, that came from engine exhaust. >> this is junk science as applied to the facts of this case. >> mcdowell said, other bigger

reputable agencies like the fbi in the ohio state criminal lab. refused to do the testing. it was too unreliable. >> these people in wisconsin said, we have never done it before. but we can try. >> mcdowell attacked the lab's data. its record keeping and its expertise. >> prior to your work and involvement in this, case you had no previous experience in conducting analysis on dr. work did you? >> no we had not done ductwork before. >> and then this question. did the lab consider other sources of soot? >> you would agree that cables are a potential source of soot? correct >> yes that is correct. >> candles. the way angler house was full of them. according to testimony from several witnesses like son, erin wangle are. maybe that's why the heating ducts were full of soot. >> do you recall if your mother ever heard burned candles in the home? >> all the time. we had tons of candles.

>> and remember those soot stains coming out of the registers in the room where kathy died? that was aaron's old room. >> those marks were actually there before i moved for college. that was back in 2004. >> the defense said the process fusion's murder scenario involving vehicle exhaust and the firmness was preposterous. it had to be the simple explanation. kathy's death was an accident. and now came the most important testimony in the defense's case. and environmental toxicologist testified. the most likely source of carbon monoxide was the water heater. >> what was the closest source of carbon monoxide? >> the water heater in the basement of their home. i think as i recall, was directly below the bedroom two floors up. >> the water heater, he said was a disaster waiting to happen. one code violation after another. >> my major concern was that this water heater was not in the open as most water heaters

are. it was in a sealed cabinet. >> closed up in that box, he said the unit could've been deprived of oxygen creating a risk of carbon monoxide. he said, venting was another problem. the vent cap was the wrong kind, in the exhaust pipe was set to low on the roof. it was all installed so poorly, he suggested that deadly carbon monoxide could've backed up into the home. the water heater was so faulty said mcdowell. >> 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. you may even find that the water heater did this. but regardless, you will not find the doctor when angler murdered his wife. because he did not. >> coming up. >> you had expert testimony on both sides of this. >> right. >> did it come down to science for? you. >> i don't think so. >> no. >> the verdict. >> we the jury find the

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♪ ♪ ♪ on a cold sunday in early march 2011. doctor mark wenger who was, standing trial for murder. seemed to want a moment with those who were standing by him. during a weekend break from the, trial he showed us around

his hometown, about an hours drive from lima ohio. his old house is still there, his sister and brother in law on the family hardware store now. it was a strange homecoming with so much at stake. he seemed so relaxed, >> i haven't worked in here since 1977 and there is some -- [laughter] >> arguing or wanted to see his mother, a chant and then goodbye, was it just for now or for? good >> well i hope this isn't the last one, i hope you get to come back next week. >> well i'm feeling pretty good about it. >> i am too. >> even on this night before closing arguments, esther and mark held to their routine, choir practice at grace baptist. ♪ ♪ ♪ mark winkler never testified on his own behalf. would it matter? , he was as quiet as ever and so hard to read, but not

esther, she was a wreck wondering what will happen, what are the jurors thinking, in a courtroom back in lima closing arguments for defense attorney chris mcdowell insisted the prosecution failed to make its case. >> did you hear them explain to you how doctor wen angler allegedly committed this crime? no. you didn't hear any of it. we didn't hear any solid theory on that. >> it was an accident, he said. >> it was the water heater. >> -- has failed to disprove it as the source. as a result there is reasonable doubt. you must return a verdict of not guilty in this case. >> in his closing argument, prosecutor -- outlined his murder scenario for the jury. the heating vents, the doors, all shut to create a direct pathway from the garage to the furnace, to kathy's room.

>> and then he started the car, or the generator, or maybe both. and then he waited. >> and in the water heater? it was checked over and over he said, sure there were code violations. >> but you know what -- . >> and then the jury got the case, two weeks of testimony, much of it dense and scientific. what mattered most to the jury? >> you had expert testimony on both sides of this. >> right. >> did it come down to science? for you. >> i don't think so. >> no. >> an afternoon passed. and by the next afternoon, their verdict was in. esther was sitting with her son, mark's family. kathy's family was seated on the other side. >> we the jury -- swear to find the defendant mark a wangle are guilty of aggravated murder. >> yes. [crying] >> doctor mark wang globe was sentenced to life in prison.

eligible for parole after serving 25 years. >> mr. wang fleur. you violated the ten commandments. thou shalt not kill, you also violated the hippocratic oath. as a doctor, you shall do no harm. >> do you remember that moment? . >> yes, i was shocked. but beyond sad. i fell and i cried hysterically. i think about it still. it makes me want to cry, because it's hard. i only have one parent now and they took him from me. so. it's hard. >> we spoke with jury members both on camera and off. they said it was the simpler things that convinced them. 9-1-1 call, the diary, the body temperature, and the malfunctioning water heater.

they didn't buy it. >> eldon and a couple of the other jurors were very not an la jolla 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. >> you ruled out the water heater. >> pretty fast, i think within the first hour or two. >> to this day do you have any idea how this crime might have been committed? >> i don't, no. >> no ma'am. >> it was vindication for kathy's family. especially her mother, who addressed the court. >> we know you have always been a very selfish person. you really did not care about our beautiful daughter, only yourself. >> you are our first two grandchildren. our family loved you. you always will be a loved. and i hope sunday we can have a connection like we had before. >> after his sentencing, mark's wife esther visited her husband in prison as much as possible. >> i just hope and pray that he

doesn't get hurt, or worse. >> detective breitigan says there were no winners in this case, he was only following evidence, he says that led to a very said conclusion about mark wenger. >> i think there was a lot of rage in him, although he wanted to live right, war he wanted to have a good marriage. i think he could not, so. >> do you think he didn't see a? way out. >> i don't think he saw way out. ♪ ♪ ♪ >> that's all for this edition of dateline. i'm andrea canning, thanks for watching. ♪ ♪ ♪ ♪ ♪ ♪ for watching. ♪ ♪ ♪ ♪ ♪ ♪ the little girl who hello, i'm craig melvin, and this is "dateline." won the heart of a big city. they call you the miracle baby. why do they call you that?