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
in april of 2007, seven months after kathy s death, detective breitigan got a search warrant for the when you are home. he had a videotape running, his officer sees the computer, papers, and mark s journals. detective breitigan says the journals really caught his attention. you have to read the whole thing. i cannot explain that, i wish i could. he was at the end of his rope. i think he felt trapped. but, now, all these months later, marco anglers life was on the upswing. he had reconnecting with an old friend, who shared his fate, esther van dine. a romance blossomed. you ended up getting married, i think about a year after kathy s death? 14 months, correct. some people might think that s pretty fast to bounce back. we ve heard that. the wedding bells had barely stopped ringing, when detective breitigan got a second search
in town, a good friend of mine, had gone to zambia with several people from his church. they learned that people and zambia were in dire need of freshwater, so march and esther join a church machine to 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, he s banging on the door. that s a detective? yeah. so you knew then? so we knew then. and the atlanta airport that there must have been an indictment, and they were at the door to rest mark. the lab results were in, on that duct work. coming up, the prosecution s case, motive. we have some theories that are pretty dark, that kind of lay out with the state of the marriage was. and means. can you tell the jury of anything you notice in that bedroom? i observe such like marking