Transcript for How a star surgeon’s lies in love and medicine came back to haunt him: Part 1
He was the closest thing to prince charming. Reporter: Bonita Alexander, a seasoned television producer, thought she'd met the love of her life. A handsome doctor. The world's most famous surgeon. That George Clooney type of feel, sexy. Reporter: Who swept her off her feet. It was like living a fairytale. Reporter: The man of her dreams was actually spinning a web of lies. That she and countless others were caught up in. This is a man who has people's lives in his hands. A Haley regarded doctor and surgeon. People could be dying. Reporter: Bonita first met Dr. Paolo macreenie when she was assigned to do a story on him. Breakthrough, a report a doctor has found a way to grow a new wind pipe -- A surgical first that could offer new hope -- Reporter: He developed a technique to replace a patient's trachea with a plastic tube seeded with the patient's own stem cells. One of his patients, a toddler from Korea named Hanna, who was being brought to the U.S. So Dr. Macareni could operate on her. She was born with no trachea, hospitalized from the day she was born. She was going to be the youngest person ever to get one of these artificial tracheas. Reporter: The doctor held a post at the karolinska institute in Sweden which hands out the Nobel prize. Did I think he was going to be part of my life? No, absolutely not. Reporter: Until she started falling for him. We met the afternoon before we were going to interview him. And it was -- it was the weirdest thing. He comes around the corner, looks right at me. In that second, something happened. I mean, I got the sort of chill through my body. Reporter: Bonita was a reporter doing a documentary on paolo, but she couldn't stop her feelings for him. It was really difficult. Because I was fall income love with somebody that I was doing a story about, which you are not supposed to do. If you get involved with somebody, your objectivity could be compromised. I agonized about it. Reporter: Bonita was divorced. Paolo said he was separated from his wife but the divorce wasn't legal yet. Still, she agreed to go to Italy with him. All the way to Venice by motor boat. He was taking me to Venice. The whole trip was so romantic. Just over the top romance. Everything. The food, the flowers, the dinners. She had finally met the person that she was supposed to be with. He would record these little video love messages to me. I cannot stop thinking of you. Especially proud that you are I love you so very much. I was very hesitant to introduce paolo to my daughter. I wanted to be absolutely sure that this was someone that I wanted to keep in my life. She thought he was amazing. Wooing her was as important to him as wooing me. My two beautiful girls. We were his princesses. It was like living a fairytale. Reporter: Paolo proposed at Christmas, giving her a ring he said cost $100,000. Paolo often visited New York where bonita and her daughter lived but never stayed long, telling bonita he had to perform surgeries around the world. That's when he told me there was this kind of clandestine network who are on call, basically, for these people. He told me that it included the Clintons and that he and bill were tight, that they were good friends, that they'd played tennis together. He adds the Obamas to this mix. As part of this vip network, he had become one of pope Francis' private consulting doctors. It sounds crazy, I know. But if anybody fit that bill, paolo fit that bill. Reporter: Bonita says paolo told her he wanted to plan their wedding in Italy, adamant they be married in the catholic church. And I said, look, aside from the fact that I'm not catholic, the catholic church is not going to marry two divorcees. Reporter: Paolo told her he would use his personal connection to the pope to see what he could do. He said, he offered to marry us himself. And I said, . The pope doesn't marry people. No, I'm serious, he wants to marry us, because we're both divorcees he thinks we're the perfect couple to push forward his forward-thinking agenda to reform the catholic church. I said, okay, maybe it's not out of the question. I felt my head was spinning and didn't stop spinning. Reporter: Paolo told her Andrea bocelli and John legend would perform at the wedding. The guest list kept growing and growing. The beckhams. The Obamas. The Clintons. For some reason Russell Crowe was on the list. Reporter: But while the wedding planning was kicking into high gear, bonita said paolo was becoming increasingly tense about work. He had been talking to me for some time about how there were people that were against him, his enemies. Reporter: And one morning she woke up and read in the "New York Times" that colleagues at the karolinska institute were accuing him of scientific misconduct. I'm like, what the hell is going on, why didn't you tell me? Reporter: Paolo headed up a research lab at the karolinska institute, one of Europe's top-ranked medical universities, and had performed three trachial facilities at its hospital. Several doctors who worked alongside paolo, some tending to the patients he had implanted with new tracheas, started voicing concerns about the new procedure. In particular, they took issue with the way he'd written them up in medical journals. We went through six of paolo's articles. We could show that there was lies and falsifications. Reporter: They filed an official complaint with the university. This was bad. It was all over the news. He was insanely stressed. I've never seen him like that. He was adamant that this was going to go away, and there was no basis to these allegations, and it was just these jealous colleagues of his who were out to get him. And I believed he was being unfairly maligned. Reporter: On top of that, little Hanna, the subject of bonita's documentary, never made it out of the hospital after her surgery. I was devastated. I had become very close to her family. It was awful. Paolo was really depressed. Reporter: But they were still forging ahead with the wedding. And bonita and her daughter made plans to move to Barcelona to live with paolo. Bonita quit her television job and pulled her daughter out of her private school. The place where you and I will live the rest of our life. I love you. I had asked a group of girlfriends to go to the spa. I'm walking to the reception desk to pay. I pull out my phone. I see this email. The subject line says "The pope." And it's from a colleague and it says, we need to talk. And it has a link to an article that shows that the pope is not going to be in Rome on July 11th, he's going to be in south America. I actually literally almost physically fell over. Reporter: Bonita started investigating paolo the way she would investigate her stories at work. She hired private investigators in the U.S. And Italy. I called the castle where he says he's booked rooms and everybody's saying they've never heard of him. I called the restaurant he said was catering the wedding, they say they've never heard of anything. Reporter: Bonita managed to get the Vatican to verify paolo was not the pope's personal doctor. She called in a Clinton contact and found out they'd never heard of paolo. She couldn't find any evidence that the Obamas knew him either. On top of it all, heartbreak. Just weeks before their wedding, the Italian investigator found records that paolo and his wife were still married. Coming up, the shocking discovery and a confrontation. I knew there was something hidden in that house in Barcelona. And I thought, the only way I'm going to find out what it is, is to go there and for him to not know that I'm going there.
This transcript has been automatically generated and may not be 100% accurate.