Good evening. Highly suspicious or just highly tragic? Those are the conflicts sides of the coin tonight. A woman found dead in her bedroom. Was it an accident? Her family wants to know, because they... See More
Good evening. Highly suspicious or just highly tragic? Those are the conflicts sides of the coin tonight. A woman found dead in her bedroom. Was it an accident? Her family wants to know, because they have the sneaking suspicions. Her autopsy includes four key words. Manner of death, undetermined. So, remember, as you watch, no charges, no arrest, just what he says versus what they say. But after the possible clues jim avila has sorted through, what would you say? Reporter: Down around mobile, alabama, near the gulf of mexico, a short drive takes you through loxley, once a sleepy lumber town, today famous for absolutely nothing. But now, on a street called camelot in a house that here passes for a castle, there is no bright shining moment, just a dark mystery of sudden unexplained death. This interview is with michael allen wool sleger. This is in reference to the wife. Reporter: The wife who died suddenly, but who was not murdered. Do you remember her falling? Reporter: Or if she was? As she falls back, she's gonna strike the floor pretty hard. Reporter: What do you really think happened, chester? Man, I hate to say this; i think someone murdered my sister. Reporter: Shirley seitz fell for doctor mike wohlschlaeger. Fell hard, and fell fast. "How do you do," to "i do," in three months flat. But shirley wasn't his first bride or his second or his third or even his fourth. Shirley was number five. Some with tales to tell about their marriage to mike and more importantly how their marriages ended. To be fair, this was wedding number five for shirley, too. And up in northern alabama, shirley's family, the thomases, wanted to be happy for her. Buff they could not. I didn't like him at all. I just have to admit that. Me being a minister, I said to her, "are you sure?" Reporter: Shirley's daughter, sharon, was ready to throw something, and it wasn't rice. Please don't do this, mama. Don't do this, please, mama, don't do this. Reporter: Whatever their worries about her latest trip to the altar, shirley's family is more than proud of her higher calling. She was an evangelist in search of a flock. Preaching the bible, spreading the gospel and singing it, too. That's her voice soaring on a recording of her favorite hymn, "amazing grace." Giving. Constantly giving. I have learned some of the best organic food there is to eat. She'd walk into burger king, and the waitress would say, "that's a pretty necklace," she'd pull it off, "well, here it is." She was the type of person that just gave herself away. We believe in that. That's part of our faith. And shirley was that type of person. Reporter: Shirley prayed with dr. Mike the first time they met. He worked much of his life as a sky practice or the, adjusting grateful patients backs in the nearby florida panhandle. Known affectionately as dr. Michael, he was a from innocent member of the medical community, smiling in the newspaper and online. But money trouble plagued the sky practice or the like a crooked spine and his financial problems troubled shirley's family, because one of her husbands, gene seitz, had died and left her withis name and a hefty inheritance. 1 million. Were you worried about her money? Yes, I was worried about her money. I mean, he come into her life with the clothes on his back. And he's a doctor? He doesn't have a home, mama? Well, he's in transition. He doesn't have a job, mama? Well, he's a kchiropractor. He's gonna get a job in alabama. He come into the marriage with a wore out pickup truck and a bunch of debt. Reporter: Her engagement ring from dr. Mike, the wedding rings. The house they lived in that first big purchase together. The family says, shirley paid it all. Mike seemed to appreciate it. Women from their church later said michael was a wonderful husband to shirley. Anything in the world shirley would tell him to do, he'd jump up and do it, you know. But who wouldn't. Reporter: Who wouldn't, because he knew where his bread was being buttered? Yeah, yeah, you said that, i didn't. Reporter: Love, marriage, and pushing the grandkid's baby carriage. Shirley's family made room for big mike. And even the doubting thomases could not guess "for better or for worse," was about to get a whole lot worse. Four years into the marriage, something is wrong with shirley. Months later, in a recorded interview obtained by "20/20, " dr. Michael would tell investigators shirley had been ill for weeks, food poisoning, thyroid problems and to cap it off, a stubborn migraine headache. She gets bad migraines maybe two or three times a year that last three, sometimes four days. Reporter: Shirley's little brother, rickey thomas, her closest sibling, who had even grown to like mike, speaks to her on the phone. And I said, "hey, what's going on with you, girl?" She said, "i'm just not well. Just pray for me." She was so out of it, she just didn't even want to talk to me. Reporter: Shirley's mom, myrtle, and brother junior thomas, drive five hours south, to the house on camelot, to see what was what. I said, come to the door, let us in. She said, I can't get up. I said, what do you mean? She said, I feel so bad, I can't get up. Reporter: The family says they'd never seen shirley like this. She had a terrible headache. She was really sick. Reporter: The family says mike tells them shirley might have fallen down these stairs a few days earlier, while he was away. Knocking down a potted plant. He later tells investigators too. I sat here with her mother and asked her, baby, do you remember falling down those steps, because they plant was knocked over. And she almost got irritate-ly mad at me, and she said, I did not fall. Reporter: Myrtle and mike nurse shirley through the weekend. They try to get her to the doctor, but shirley keeps putting it off. Mike gives her migraine medicine. It seems to do a world of good. And by sunday night, shirley is even sitting up, eating and talking. I said, now, shirley, you better lay down and go to sleep. We don't want that to start back again. And that's the last words I ever said to her. Reporter: The next morning, mike, who said he had been spending his nights on the couch, goes into the bedroom once again. And she wasn't responsive. So I walked over and I turned on the light, and her lips were already blue. Reporter: Mike yells for myrtle. She's not breathing, call 911. Reporter: Steve brannan is a former fbi agent, now a private investigator hired by the thomas family. He showed us around the house on camelot. So, when myrtle gets in here, what does she see? She sees shirley on the floor, by the bed. Reporter: On the ground? On the ground. And michael beginning cpr. Reporter: Myrtle knows it's too late. I said, "mike, shirley's already gone." Reporter: Shirley is dead. Precious. She was precious. If I can be a third of the woman that she was, I'm -- I'm blessed. I loved her. She was my best friend, jim. And she didn't deserve what happened to her. Reporter: At the hospital, where shirley is pronounced dead, a distraught dr. Mike demands answers. First thing mike said, I'll never forget it. He said, "well, I want an autopsy." Reporter: Mike says he was desperate to know whether he could have prevented shirley's death. I said, I'm trying to get a handle on what's going on, because not only have I lost my wife, but now, I don't know whether I could have saved her, if I could have gotten her to the doctor. Reporter: And things are about to get worse for the grieving widower. Because as they begin to settle the estate, shirley's family turns on him. Chester is sorting through shirley's fortune. What's left of it. What happened to her finances? He soaked her dry. I don't know another way to put it. Reporter: Still ahead, dr. Mike gets his answers. An autopsy reveals the cause of death, and it was no migraine. But was it the other m-word? Stay with us.
This transcript has been automatically generated and may not be 100% accurate.