We start with a question, how far would you go to get love, to death revenge, pay for college or have a baby? Those first three, love, money revenge all come into play in the first cat and mouse game.... See More
We start with a question, how far would you go to get love, to death revenge, pay for college or have a baby? Those first three, love, money revenge all come into play in the first cat and mouse game. That's right, David. A woman scorned and looking for payback, literally. What turned a shy, southern belle into an obsess the steel mag knoll gentleman, whipping through wigs and disguss, playing detective, all to get back what an ex-boyfriend has taken from her, not a life savings but her pride. Reporter: Welcome to los Angeles and a very serious game of hide and seek. Where this woman spends a great deal of time looking for this guy -- and he spends a great deal of time looking over his shoulder trying to avoid her. He's also trying to avoid this woman, and this woman, and this woman. What's at stake here? Well, she could collect nearly $2 million or go home broke. It's a story of deception, dollars and disguise. Katherine Underwood is trapped in a bad relationship and even though the romance ended a long time ago, the South Carolina native simply can't walk away. Her former boyfriend, on the other hand, wants to run away. A departure from the avalanche of affection he once bestowed on Katherine in aspen, Colorado. What were your first impressions that first meeting of him? I wasn't really that fond of him. He was nice, just not necessarily like any of my other friends. Reporter: First impressions on that snowy night back in 1994 may not have been memorable. But his name certainly was. Budimir Drakulic. And his middle name was persistence. He had found out where I worked, and came walkin' into the restaurant, and just appeared. He wanted to know what I was doing when I got finished, and I met with him. Reporter: It is the textbook definition of "Opposites attract" as the ucla professor of biomedical engineering falls for the coat check girl. How did he begin to win you over? Because you weren't interested at first. He was just so determined to get to know me, and I was so determined that I wasn't interested. And I think I was just taken by his determination. Reporter: The professor professes his love for Katherine. He told me he loved me on the first night. On the first night? He called her every day, he told her how wonderful she was. He kept talking about the life that they would have together. Reporter: Budimir wines and dines Katherine. He flies her to his home in L.A. So the two can spend more time together. Eventually you did feel like you grew to love him? I did. Were you talking marriage? Yes, we were talking marriage and children. Reporter: Katherine is fully invested in the relationship and the long distance romance blossoms. After about eight months, budimir pops the question. Just not the one she was hoping for. What did he ask you exactly? He asked me for $5,000. Reporter: Budimir was away on business and, according to Katherine, needed to pay child support and couldn't transfer funds into his account. Did you have any doubts, any second thoughts at all about loaning him that $5,000? Well, no, because he was -- he had a good job. And I for sure thought he would pay me that back. Reporter: Donna Anderson has written about Katherine's case and has counseled thousands of women to spot the warning signs. The first time that he asked for money, he didn't ask for it for himself, he asked for it for his kids. And it was kind of like a trial balloon, you know, just to see if she would even respond to that. And she did. Reporter: One month later, another story, another request for cash. He asked if I could loan him 5000 more dollars. It was for his mother who didn't speak any English. And did you have any reason that point to think, this sounds a little fishy? Well, well, no. He had several phd's, he was very intelligent. I thought he was a professor at ucla. Reporter: The money grab continues. This time, Katherine says, budimir Drakulic tells her he's at Edwards air force base conducting a top secret project. So secret, budimir actually whispers during phone conversations because the not supposed to be making outgoing calls from his location. The project, once completed, would earn him millions, but he would need $35,000 first to finish the research or risk losing everything. And I felt really bad for him. Was there any part of that story that rang untrue for you? No. I wish it did. Budimir Drakulic targeted her because he knew that she was vulnerable. Reporter: Katherine does indeed have money, and not the kind you make by checking coats. So the money you inherited mostly came from your grandmother? Yeah, that's right. How much money, when you met him, did you have in savings? I had around $450,000. Reporter: Nearly $500,000? She would not have it for long. The fangs of Drakulic are out now as he begins to suck Katherine's bank account dry with a never-ending series of withdrawals that Katherine reluctantly approves. He needed $8,200 and 9, $9,800, and $9,700. So Katherine, how much money total did you loan budimir? I believe around $400,000. You loaned him your entire life savings? I loaned him everything. Reporter: And despite the endless borrowing, Katherine stays in the relationship. A combination of misguided trust and a very real fear. Once Katherine Underwood had invested $100,000, $200,000, she began to believe that the only way she could even get her money back is if the project became a success. It stretched out year after year? Yeah, I felt trapped. The more I gave him, the more scared I was. Of losing all your money? Yeah. Reporter: When we return,
This transcript has been automatically generated and may not be 100% accurate.