for your fibromyalgia pain. Reporter: Waseem daker is finally on trial for a brutal attack on a 5-year-old boy and the murder of the boy's mother. Prosecutor jesse evans says he is the worst kind of... See More
for your fibromyalgia pain. Reporter: Waseem daker is finally on trial for a brutal attack on a 5-year-old boy and the murder of the boy's mother. Prosecutor jesse evans says he is the worst kind of stalker, the kind that becomes a killer. What picture do you develop of waseem daker? A psychopath. You could go your entire career as a prosecutor and not come across somebody with the issues that he has. Reporter: Then on the eve of trial, daker has a surprise. He sheds his prison jumper for a suit, gets a haircut and chooses to represent himself. The decision seems part madman, part genius. I think that he considers himself to be exceptionally intelligent. I think that he had a lot of time to peruse the case and decide that he could represent himself better than anyone else. And I think it also was driven by his opportunity to confront lottie spencer blatz. My question is -- Reporter: During the three-week trial, daker is soft-spoken and plays the part of counselor. He seems out of his depth, and prosecutors say "out of his mind" as he argues he wasn't lottie spencer's stalker. He was her lover. Judge, she's alleging she has never had a relationship with me. Because I'm not allegedly. I never had a relationship with you. Judge, can I speak without being interrupted by the witness, please? Reporter: But daker is also facing a couple of tough pieces of proof. First, proof he obtained disturbing materials before the murder. Books like "techniques of silent killing" and "kill without joy." And many of those books are hauntingly true to what we saw in the scene, including using an ice pick. That's what happened to karmen smith. The assault on nick smith, he was grabbed by an arm from behind. That was displayed in the books. Reporter: Even more damning is a crumpled up letter daker wrote to himself while locked up briefly before the murder. In it he scribbles a threat to lottie, "she will pay for what she has done. That's what keeps me alive in jail, plotting to destroy her, though I will let her live." Prosecutors say it might be a hint at daker's motive in killing karmen smith, an act of revenge against lottie. Now, the stalker has control of his victim once more in court. This incident where you allege the defendant put a gun to your head, when did that happen? It happened more than once. How many times? With the gun or the knife? Oh, there's a knife now. Tell us about the knife that you didn't tell us about yesterday. Tell us about it. Reporter: Daker seems to enjoy badgering lottie, who has her identity hidden from cameras, contemptuously asking her questions that he already knows the answers to. Miss smith was killed on OCTOBER 23rd, 1995, WAS SHE NOT? Reporter: What does it mean has decided to represent himself? You know that he's enjoying every little word that comes out of his mouth, that he gets to stand there across from you after all the things that he did. It's torture. It's torture. Reporter: The judge has set some rules for daker. He cannot cross this line of tape on the floor, approach anyone or handle evidence including knives and an ice pick, but he still has plenty of opportunity to get inside lottie's head. What other threats did the defendant make to you? That you'd kill yourself in front of me if I wouldn't talk to you. That you're going to -- that you wanted to slit my daughter's throat in front of me. Keep going. What else? What other threats? Did the defendant ever threaten to kill you? Yes, he did. Did he ever threaten to kill your daughter? Yes, he did. Reporter: What benefits do you think you wound up gaining from the fact that daker decided to represent himself? The big benefit for us is he came off so creepy. Did he ever threaten to kill your grandchildren. You did. Reporter: It is surreal, daker acting the cool counselor, referring to himself in the third person as lottie identifies him as a monster. A prosecutor's dream come true. Daker actually wants lottie to recall each and every threat and seems to enjoy hearing lottie analyze his disturbed personality. Any other threats he's made? Please, share them. If you don't talk to me, if you don't forgive me, if you don't be my friend, I'm going to kill myself. He was very manipulative. And, yes, I should have never dropped any charges on you. Never. And I regret that each and every day. Are you done? He was calm as a cucumber. He has no emotions, no feelings, zero. Zero. Was there any indication that the defendant had been this your home? Yes. Karmen was dead. What he -- nick was stabbed. You were there. Judge, this is totally unresponsive to the question. You asked. Reporter: You seem to change over the course of going back and forth with daker. You seem to kind of find a resolve in yourself. I could tell that he was really enjoying it, and I didn't want him to have any more power over me. You said that if I called and pressed charges, you were going to ruin me. That you would let everyone see my journals. So after the defendant put a gun to your head, you chose thought to mention this because he would expose your journal. During the whole course of your harassment and stalking was for it to stop. I kept on thinking poor nick stabbed him 18 times and murdered his mom. And if he's going to do it, I've got to be strong for him, to show him that we can do it. We can do it. Reporter: In no small irony, the day nick testifies is the day his mother would have celebrated her 47th birthday. He is now a grown man, 22 years old. The person in the room grabbed me -- Reporter: But on the stand he relives being a little boy stabbed by the man in the black mask. He covered my mouth and then kept stabbing me and then -- Reporter: Unmoved, daker immediately tries to poke holes in nick's story. Do you remember telling detective randy harris and detective mary findley that you No. Do you remember telling them back in 1995 that the killer's eyes were blue? No. I was in the hospital and had gotten stabbed really bad by the accused, so I don't really think that was a very good time to be asking a 5-year-old questions like that. Reporter: Did you feel victimized again by him? Not exactly. I knew that's how he wanted to make me feel, so since I knew that, I did my best to not let myself become a victim again. Reporter: What were you telling yourself when he started asking you questions, making light of what he had done, pretending it hadn't happened? Well, he was pissing me off, the way that he was asking me questions. Do you recall that statement. He was trying to confuse me and make me remember things that I didn't remember. Reporter: For nick, he literally wound up facing down the bogeyman. This is the monster from his childhood nightmares who he knew was real. He didn't know where he was. We tell our kids there's no such thing as monsters, hoping to comfort them so that they'll feel safe in their home. And then you have a person like waseem daker, who's proof positive that that's not entirely true. Reporter: Then there's what prosecutors called the smoking gun, hairs found on the dead body of karmen smith. Daker said he had never been in the house, yet the dna tells a different story. We have a hair linked positively to him with dna science not just on the deceased body but it's on karmen's shirt. It was the nail in his coffin.
This transcript has been automatically generated and may not be 100% accurate.