Reporter: Imagine walking into a hotel elevator in Miami. Then somewhere, somehow, you can't remember exactly -- a stranger attacks you. You're begging for your life, and for someone, it's funny. They... See More
Reporter: Imagine walking into a hotel elevator in Miami. Then somewhere, somehow, you can't remember exactly -- a stranger attacks you. You're begging for your life, and for someone, it's funny. They just laugh. Reporter: You black out. Your lifeless body is found naked, savagely beaten and raped and discarded in a vacant cul-de-sac ten miles away. And you don't understand it, going on. Reporter: Days and nights pass. No one's arrested. Your body begins to heal. Your psychological scars remain raw. Many things you are blaming, you are asking yourself a lot of questions. Why? Did I look different? Did I act different? Reporter: That was where 23-year-old inn budnytska found herself in the spring of 2006. Angry, depressed and desperate for answers. But what she didn't know was that there was a man she'd never met who was now fixated on finding her attacker. Any case can be solved. But you need a lot of hard work, a lot of perseverance. But you need a lot of luck, too. Reporter: Private investigator ken Brennan was hired by the hotel's insurance company, which was trying to fend off a lawsuit inn had filed. From the get-go, this P.I. Let it be known he was interested in more than just a paycheck. I inform my clients that right from the very beginning that, listen, I'm here to find out what happened. If you want to find somebody, find out what happened, what the truth is in a situation, I'm the guy for you. But otherwise, I'm not interested. Reporter: Brennan was indeed interested in the challenge of this mysterious case. Something that I was interested in. I like to do puzzles in the newspaper. I enjoy that type of thing. Reporter: On top of that, for as long has he can remember, Brennan has had a certain fastidiousness. Got to pay attention to all the details. Reporter: Which extends into every facet of his life. It was that obsessive-compulsive personality which drove Brennan to sift through every frame of the hotel security camera footage from the night of inna's attack. Hours upon hours upon hours to do so. Reporter: Hard labor, which would lead to the one frame of video that would blow the case wide open. Brennan's convinced that this big guy, who just happens to be getting into the elevator with inn the last time she's seen on camera, is the suspect. He believes the mystery man attacked inn somewhere in the hotel, stuffed her in his suitcase, then drove her out to that vacant lot and dumped her body. He believes he kills her. Okay? He didn't stuff that girl in the suitcase thinking that she was alive. He stuffed her in there thinking she was a corpse. Reporter: It's a decent theory, but so far no one else seems to find it compelling. In a foggy and fragmented account, inn has told police she believes she was raped by two white males with Latin accents, not a lone black man. But Brennan is undaunted. I'm so far into this investigation now there's no way I'm going to let this guy go. I'm going to track this guy down. Reporter: But how to identify a man only seen on videotape? An unbelievable guessing game is the only hope. Based on a t-shirt worn by another man seen with the suspect, Brennan guesses they're with a boat engine company and more likely working at the boat show. Maybe he got his t-shirt at the food court where sometimes they're handed out. Random? Yes. But also right. Center plate, the catering company running the food court, says it can't identify the man, but someone fitting his description was hired out of new Orleans. Which has since been devastated and depopulated by hurricane Katrina. In New Orleans, the city that thought it dodged a bullet is now a disaster zone. Doesn't work here anymore. He ree he's gone. Hurricane Katrina happened. Reporter: Fortunately, thanks to a police contact in new Orleans, brennan,against all odds, has tracked down his suspect's name. But get this. They come back and they tell me the guy's name is Mike Jones. I'm like, you got to be kidding me. Mike Jones? What is there, like 10 million of them? Reporter: Mike Jones. Mike Jones, that's the guy's name. I said, geez, you know -- Reporter: That's as generic as you can get. Yeah, I mean, the guy's name was like, Mikhail gorbachev or something, you know, it would be a hell of a lot easier to track down. Reporter: At least there is a middle name, lee. So now, after some basic detective work, Brennan's theory takes a big leap from speculation to certainty. Well, what I did was I took that information, I went back to the hotel registry, and lo and behold, what do I find out, that there was a Michael lee Jones Jr. That did stay at the airport regency hotel. And -- Reporter: That's a pretty big moment. Yeah, well -- that's an ah-ha moment where you say, hey, I was on the right track. I got the right guy. They notated on his card that he did work for center plate. The Mike Jones that I was looking for was the same Mike Jones that was in Miami at the Miami boat. Okay? That I know. Now, I just got to find out, where the hell is he? Reporter: Brennan's gut instincts have been on a true winning streak, so he figures, why not roll the dice once more? Michael Jones doesn't work for center plate anymore, but Brennan is willing to gamble he hasn't switched careers. I said, the likelihood is that even though he doesn't work for center plate anymore, he's probably going to work for one of their competitors, doing the same line of work. So, I asked the guy from center plate, I said, give me a list of your, like, top ten competitors in this business. Reporter: Starting from there, Brennan digs deeper. He builds a master list of the major catering and concession companies in the country. He calls them one by one looking for a Michael Jones. Near the bottom of that list is a company called ovations, based in Tampa. It just so happens that I was on my way over to Tampa at that particular time. I made an appointment to see him in person. I talked to the CEO of the company. I said, listen, do you have a Michael lee Jones working for you? He said, listen, I can't help you with that. He says, I can't give you any information about my employees. You require a, you know, I'd require a subpoena to be able to rereese release that to you. Reporter: They want a subpoena, what does that tell you? So what it tells me, that the guy works there. You know, why else ask for a subpoena? You know, I talked to, you know, 35 other companies and nobody had an objection to telling me that, no, no Michael lee Jones worked there. Reporter: At this point, it's time for Brennan to cash in his chips with Alan Foote, the miami-dade detective who'd originally handled the case and who has been willing to let Brennan run with it. Now is the time to call my buddy, detective Foote, and tell him, listen, I need a subpoena. Reporter: How urgent was it for you to get that subpoena? I obtained a subpoena for Michael lee Jones' records. As soon as I received the information, I faxed the information to ken. It was very important, and fortunately he was able to obtain the subpoena for me and, get it faxed over to the company at ovations, to the CEO over there while I was still present. Reporter: Ovations finally releases the information. And just as Brennan suspected, Michael Jones is on the payroll. He's currently working at a minor league baseball park in Frederick, Maryland. So, I said, listen, you know, we got to get some DNA from this guy. Either from voluntarily or without his knowledge because I have a DNA profile from the victim and we have to match it to somebody. Reporter: At long last, ken Brennan and the mystery man with the suitcase are about to come face to face. Now's the time. Now's the big day.
This transcript has been automatically generated and may not be 100% accurate.