Transcript for Police interview 11-year-old about the murder of his father's fiancee: Part 2
??? ??? Reporter: It happened inside this Pennsylvania farmhouse. The general reaction around town and the area, really, was one of shock. Reporter: Just 18 hours after the murder of 26-year-old Kenzie Houk, Pennsylvania state police have made an arrest. The suspect -- not some hardened criminal. It's an 11-year-old boy. Jordan brown, accused of gunning down his pregnant, soon to be stepmom. The tiny town of wampum, with a population of roughly 600, now has millions of eyes upon it. Jordan brown was just 11 years old last February. That mug shot of Jordan that sort of became an icon of the story spread across the world. Reporter: This is the mugshot that was taken. I was crying in the picture. I was crying that whole night. I didn't understand what was happening. Reporter: Did you understand what you stood accused of? No, I didn't understand. Reporter: What do you see in this mug shot? I see absolutely who just committed a murder, that's why there's a mug shot. Reporter: Retired state police corporal Jeffrey martin says the first critical clue was from the autopsy, which revealed the single gunshot to the head, and the shotgun pellets that killed her. I've never expected to have the murder weapon to be a shotgun. Reporter: And so what is that telling you in terms of a suspect? It's more of a weapon of opportunity, it's not a weapon that someone's gonna carry across the field or carry up a driveway. It's three feet long. Reporter: At the brown's farm house, investigators found a collection of weapons, handguns, rifles, several rounds of ammunition and a child-sized shotgun that belongs to Jordan, a gift from his father for Christmas. Tell me a little bit about the hunting culture in rural areas of Pennsylvania. It's fairly common, most -- especially young males, would grow up with learning to shoot firearms. Reporter: So it's not unusual for a kid to have a shotgun, a hunting rifle? No. Reporter: How often did you go hunting with your dad? Well, as much as he would take me. Reporter: But two police officers at the scene are suspicious when they take a whiff of that barrel. It starts to seem like, well, a smoking gun. We had a youth model shotgun in the house that had smelled like it recently had been fired. Reporter: But what really turns the case, police say, are the additional interviews they conduct with Jordan and 7-year-old Janessa on the day of Kenzie's murder. So what made you suspect Jordan? When we interview someone, you expect them to give their account, wait a little while, we interview them again, and they should give the same account. And I don't know if that happened in this case. Reporter: Investigators say in his second interview, Jordan described that black truck he saw that morning differently. And he now added that there was a person inside it. Now, all of a sudden, someone was ducking down inside the truck and they had a hat on. His information changed. Reporter: And police believe the strongest piece of circumstantial evidence comes from Kenzie's 7-year-old daughter, Janessa. Police say at first she didn't report anything out of the ordinary that morning. But when she is re-interviewed, she has a startling new recollection. Police say she tells them she saw Jordan moving his guns that morning. And then -- She told me that when she was waiting downstairs for Jordan to come, she heard a big boom and she identified it as the sound of a gun. Reporter: Do you remember doing anything with those guns that day? You never brought the guns downstairs. No, I never touched them. Reporter: What was the motive in your mind for Jordan to do this? In my opinion, jealousy. Jealousy of the impending birth. Reporter: And Kenzie's father told us he had seen another side of Jordan. He just seemed like he was a troubled kid. He just didn't seem like he was a real happy kid. I don't get it. Reporter: Back at the Lawrence county jail after Jordan's arrest, Chris is separated from his son. And horrified by the sight of him behind bars. The smallest jumpsuit they had, they put on him. And he -- it was just rolled up and rolled up and rolled up. And I remember just big balls and cuffs around his -- Reporter: Like a Halloween costume. Oh, yeah. Reporter: Defense attorney Dennis elisco rushes to the jail. It was beyond surreal. He was in a state of absolute shock. He couldn't understand why he couldn't come home. You know, at 11 years old, that's so hard. The whole situation, I'd say is heinous. It's difficult to charge an 11-year-old with homicide. Reporter: So you have to be really sure. You have to be sure enough to charge him, yes. Reporter: Prosecutor John Bongivengo tells reporters he is confident in his arrest. Especially because Jordan's clothing showed some evidence of gun residue. I have a shotgun blast to the back of the head. It's consistent with a 20 gauge shotgun shell. I have a 20 gauge youth model in his room. It smells like it's recently fired. And he's got gun residue on him. At this point, that is more than enough. Reporter: Police found three 20 gauge shell casings outside the home, and one in particular caught their eye. That shell was found adjacent to the driveway in late February in pristine condition. Reporter: In that second interview he had with police, Jordan refers to throwing lint out of his pocket on the way to the bus. Mcgraw thinks he threw something else. Reporter: You're convinced that it was the lethal bullet, from this 20 gauge shotgun? Correct. Reporter: You didn't immediately assume that he was innocent. Correct. I kind of took a step back and thought, "Could this have happened?" I didn't see any signs. I didn't want to believe it. Reporter: "Could Jordan have done this?" Yeah, right. So, but at the same time -- I said, "If he is responsible for this, he needs help." An 11-year-old couldn't plan their own birthday party, let alone, you know, to think that they could do something like that.
This transcript has been automatically generated and may not be 100% accurate.