Transcript for Legendary detective joins JonBenet Ramsey's murder investigation: Part 6
It was natural for her. I competed with jonbenet. She had all these wonderful costumes and outfits, and she had this presence. Third runner-up, jonbenet Ramsey. It wasn't really a competition to her. It was more of like, this is fun. Like, let's go on stage and do that. My name is jonbenet Ramsey, and I'm 5 1/2. What is your favorite animal at the zoo? The monkeys because they laugh and hang around. Today, that little girl would be 30 years old. I was her age. She would be my age now. She would be pursuing her own career. She never got to grow up. She is frozen in time now. Well, the police were convinced pretty early on that Patsy and/or John were involved. And you had a district attorney's office that was saying not so fast, and that created enormous tension between the two. Did you hear anything yesterday? I think there are some new developments. Alex hunter, the district attorney, wanted someone to come in with fresh eyes in this case and look at it from the perspective of a defense attorney. Who might have killed jonbenet as an intruder? Not just the parents, but from the outside? The D.A. Alex hunter brought Lou smit out of retirement to dry to do the case right. One of the great challenges is to try to do the case right. And you know, I think we're making efforts to meet that challenge by involving people like Lou smit. The legendary investigator Lou smit. He had a history of closing cases. He had such tenacity. He was a bulldog. Once he got something in his mind -- you know, once you got the reins in his teeth, he was not letting go. Lou smit was my father. He was just known as the, you know, detective that solved cases. When he got to a, murder scene, he spent time dictating everything he saw -- where the sun was in the sky, what the weather conditions were like, what the neighboring houses looked like. Our grandfather was a detective on one of the biggest unsolved murders in our generation. Prior to this case, Lou smit had investigated over 200 homicide cases that led to arrests and convictions. Lou dedicated a big part of his life to finding jonbenet's murderer. When he started his investigation, he felt like everybody else did that it was probably one of the two parents. It seemed as though the parents were probably involved in it. I thought this was be a fairly easy case. I thought it would be a slam dunk. And I even remember talking to my daughter. I kind of joked with her, saying that, you know, if somebody did get in the house, uh, it must have been Santa Claus coming down the chimney. It was within a couple of days after my dad started on the investigation when he had a chance to review pictures the evidence that he was already saying, I think that they need to look the other way. He was already noting in his journal that he felt that they needed to look at an intruder. Lou came up with the intruder theory. You can't think about that theory without associating it with Lou smit. The first thing that stood out to him was an open window in the basement. There was a suitcase propped up against it. He didn't buy the Boulder police department's conclusion that no one could get in that basement window. He began to say maybe somebody did get into that house. I'll show you how easily it can be done. So, what did Lou smit do? He went and climbed in the window himself with a camera rolling to prove that it could be done. It really wasn't that difficult coming in that window. But some say that the idea of somebody going in the window is complicated by something else that's spotted in the images of the crime scene. When you go to a photograph of the aual window, there are cobwebs in the window, which could support that no one did go through this window. The big question is, could you have gotten through this window, this small window, without disturbing this cobweb? I think the answer to that is maybe. But the other important point is how soon was this picture taken after jonbenet was killed? Because spiders can replicate webs very fast. Also found in the basement Also found in the basement by jonbenet's body, a shoe print. Hi tec brand, which didn't match any of the shoes in the Ramsey's house. And then there's E high tech footprint as well. Then there's the high tech footprint found next to jonbenet that I think the investigators believe, and maybe rightly so, that that's the bad guy's footprint. Some argue the footprint could have been inadvertently left by police officers there at the scene. But another factor in Lou smit's investigation, two strange marks on jonbenet's face and back. The marks themselves, uh, both on the back and on the face, were the same distance apart. Suddenly, a little light went on, and it was just like, uh, wait a minute. It was a stun gun. Smit looked at other murders where a stun gun was known to have been used. He examined images of a crime victim who had a known stun gun injury. And the marks are very similar to the face of jonbenet. He also looked into an experiment performed using stun guns on pigs. These marks were also the same as the marks found on jonbenet. When we did the pigs, we get perfect marks, just almost like on the back of jonbenet. This brings back our grandpa's whole motto that things are usually what they seem, don't make it complicated. There's no reason at all for the Ramseys to use a stun gun, and the Ramseys don't have a stun gun. If it's not a stun gun, what is it? That's the question I always ask. You tell me what it is. So, everybody sort of pooh-poohed and ridiculed the intruder theory until Lou smit started to stand up and point out things that everybody else, from the Boulder pd to the general public at large, had overlooked or dismissed. He said, wait a second, we need to look at this again. It actually is possible. It actually is plausible. And in his view of it, it's actually the most likely thing that happened. The police and the district attorney are at odds. The D.A. Is looking at the intruder theory. The police are focused on the parents, but both want to get the Ramseys to come in for a formal videotaped interrogation. Go back to the damn drawing board. I didn't do it. Lou smit thought that the Ramseys were being targeted unfairly. I thought there was something drastically wrong. I had scene evidence of an intruder.
This transcript has been automatically generated and may not be 100% accurate.