Reporter: Take a look. A closer look at the security cam footage and watch Michael Jones exiting the hotel with his suitcase. Do you see what ken Brennan sees? Take a look at this guy. Just take a... See More
Reporter: Take a look. A closer look at the security cam footage and watch Michael Jones exiting the hotel with his suitcase. Do you see what ken Brennan sees? Take a look at this guy. Just take a look at the video. I said, look how nonchalant this guy is. I said, he believes he murdered this girl, stuffed her in a suitcase and he's looking to dump her. And look at the way he walks off the elevator, and walks through it like he's -- like he's whistling. Like he wasn't a care in the world. Reporter: That's what leads Brennan to a chilling conclusion. There's a problem with this guy. He's done this before. Reporter: Brennan knew Jones' work took him to cities all over the country, giving him plenty of opportunity to meet new women and then disappear. What better occupation for a serial rapist or a serial murderer? Reporter: So when detective Foote tells Brennan that Jones copped a plea with a two-year essential sentence for the attack on inn, Brennan plays his final ace. I said, don't worry about it. Trust me, you take his DNA, put it into codes, you're going to get a hit. Reporter: And that's the national register The national registry that the FBI -- the DNA data bank that the FBI has. Reporter: It takes more than a year, but Brennan is nothing if not patient. I said and when his profile goes out, there's going to be other hits from people he's done this to already. There was no doubt in my mind. I was certain of it. Reporter: Then, in a word, bingo. I was notified by them that they had DNA that had matched my case. Reporter: Detective terry thrumston had a cold case up in Colorado Springs. The crime occurred in December of 2005, about nine months after the attack on inn budnytska in Miami. And, guess what? About three months after Michael Jones had left New Orleans in the wake of hurricane Katrina, he was working concessions at the Colorado Springs world arena before taking the job at the ballpark in Frederick, Maryland. He traveled all over the United States for his job and he was good at being a rapist. Reporter: The Colorado victim, 41-year-old Jennifer Roessler, seen here just minutes before the attack, leaving a local convenience store. On that night her whole life changed. She was a woman, alone, walking at 2:30, 3:00 in the morning. The man asked her if she wanted a ride. She said yes and got in his vehicle, got to her apartment. He asked for a drink of water. When I asked him, you know, you need to leave, you know, I was going to go to bed, and he just -- he was like jekyll and Hyde. He just -- it just -- I could just see the monster come over him. And then he sexually assaults her at that point. He wasn't nervous. He was calm. It was like we was on a date. And I knew, terry, I knew this happened before. I've just -- I had a feeling this has happened before, because he was too calm. She wanted to confront him. She wanted justice for what happened. I just want you to catch this guy. And I'm -- you know what? I'm working really hard. I know you are. Reporter: Now, with the DNA hit, it looks like justice may finally be within reach. But it's still far from a done deal. Roessler's decision to let Jones into her apartment raises the possibility that the sex was consensual. And worst of all, just before the start of the trial in January 2009, tragic news. I kept trying to get ahold of her and couldn't get ahold of her and I didn't find out until the beginning of December that she had passed away. It was a shock. Reporter: Jennifer Roessler had suffered medical problems unrelated to her rape. Now, without the star witness, the best chance to put Michael Jones away for a long time is fading fast. But thrumston isn't going to let it go, and takes the case to trial anyway. When she died, the case didn't die for me. I wanted to see it through for her and for the other victims. Reporter: The trial is something of a reunion. Miami detective Alan Foote heads to Colorado to testify. Inna testifies too, driven by a seething desire to confront her attacker. I wanted so much, just to look into his eyes, and just, I had a question, why me? What did I do? I mean, why me? Reporter: And now, to dispel any reasonable doubts, thrumston has found a silver bullet. Yet another rape victim with a DNA hit. There was never any hesitation to go and testify against this man. I was more than happy to be there. Reporter: This woman, we're calling her Rachel, may have been Jones' fist first victim. It was back in New Orleans in 2003. Her story should have a familiar ring. A stranger in a car, a ride and a rape. I screamed with everything I had. And the reality was, just, there was nobody there. It was -- there was nobody there. Reporter: But now, Rachel's voice will be heard. On the stand, she makes a perfect witness. She was able to describe exactly what had happened to her six years later. In full detail of what had happened without a doubt. Reporter: And her reputation is unassailable. I'm a working professional and I'm a mom. Reporter: And above all else, this -- a composite sketch Rachel made with New Orleans police of the man who raped her. It looked almost identical to what Michael lee Jones looked in the courtroom. Seeing that sketch next to his face, it was extremely satisfying. I just felt, like, yes! Reporter: In the Colorado trial, the defense tries to argue the sex with Jennifer Roessler was consensual, but with DNA hits from multiple women all claiming rape, and Rachel's sketch? As ken Brennan might say, no dice. Within a couple hours, the jury came back and said he's guilty. Reporter: Jones is slammed hard. A sentence of 24 years to life. By the time he's eligible for parole, he'll be just shy of his 60th birthday. And I feel happy that the criminal is where he's supposed to be and he never going to hurt nobody in the future. Reporter: You gave almost two years of your life to this case. How did it feel to finally see this guy brought to justice? I gave two years of my life investigatorial-wise. But you know, the victims give a hell of a lot more. They're the ones that should be commended for this. I can only do the investigation, and you know, make an arrest, but they're the ones that put them in prison, you know? The victims are the heroes here. They're the ones that have to get on the stand and say, "This is what this guy did to me, this is when he did it to me, this is how he did it." You need to go through this, as painful and as traumatic and embarrassing as all of that might be, you have to do that, because you just -- you never know how many other women may have been impacted by this person. Reporter: Inna doesn't feel like a hero, just a survivor. I wish it never happened to any woman. I wish it never happened to nobody. Reporter: Inna settled her suit with the hotel. She still struggles with depression and anxiety, but she says she has managed to move on with her life. Detective Alan Foote retired from the miami-dade police with a smile on his face and a new opinion of private investigators, at least this one. You weren't that crazy about private eyes to begin with. Did this case change your mind at all? In respect to ken Brennan, it did, yes. Reporter: But private eyes in general, not so much? I still have the same opinion about private investigators, but I respect ken Brennan as a person and as an investigator. I could count on him, glad to know him. Reporter: And as for the man himself? With the case closed, Brennan can treat himself to a celebratory cigar. And a profound sense of satisfaction. I've been doing this since 1975, and in the multitude of cases I've done, this is by far the most rewarding.
This transcript has been automatically generated and may not be 100% accurate.