Transcript for Teacher's gruesome 1992 death launches decades-long mystery: Part 1
Reporter: Lancaster, Pennsylvania. A popular destination and wedding location, attracting tourists for the beautiful venues, food, and flowers. But is it possible that one of these wedding professionals responsible for creating people's most cherished moments, is also responsible for a brutal murder 2 1/2 decades earlier? 25-year-old Christy mirack was murdered. This girl was also severely beaten around the head and neck. This quiet neighborhood is in disbelief that such a tragedy could happen so close to home. The last person anybody would have ever linked to her murder or suspected. Reporter: This story does not begin at a wedding, but during another time of anticipation and excitement. Days before Christmas, 1992. It's very scary. This is such a quiet neighborhood. We keep our doors locked. This is horrible. Reporter: Christy mirack grew up in Pennsylvania, in coal country. The middle child of a close-knit family, and older sister to Vince. What was she like as a sister? She always was funny. Very talkative, very opinionated. I think she would make a room kind of lighten up if it was down. She had a smile that just drew people to her. Reporter: Annie Adams was one of Christy's best friends. When we were in high school there was a show on TV called "Dancing on air." Reporter: A music show for teens. That's all she wanted to do, she was just -- she was getting on that show, she was getting on that stage. And she did get us on the stage. Reporter: That's Christy on the right, next to Annie. ?????? Christy mirack! Reporter: By December of 1992, she was living in Lancaster, Pennsylvania. Her one goal and dream is that she always wanted to be a schoolteacher. Reporter: And she got that job. Let's go with what we have up here. Reporter: Teaching sixth grade at roherstown elementary school. Principal Harry Goodman hired her. There are certain teachers where you can walk in their classroom, and you almost get chills because they have the kids captivated. And she taught with her heart. What would you look at, Emily? She was so cool. She was young. She had good clothes. She had that big smile, pretty blond hair, and just that energy, it just made you want to spend more time with her. Reporter: December 18th, Christy has dinner with her brother Vince. It would be the last time he would see her. It was just like any other time you say, "Good-bye, we'll see you in a couple days," and, you know, assumed we would. Reporter: The evening of December 20th, Christy is at home preparing for the holiday. Wrapping copies of the book "Miracles on maple hill" for each of her 24 students. She wrote a message to them. "Merry Christmas and have a great year." I did talk to Christie the night before. We always made plans to get together on Christmas day. Reporter: The next morning is a chilly one, with temperatures below freezing. Christy is up before sunrise. It started out like any other day. Christy always got up very early in the morning. On this particular morning she sat on the couch, in a blanket and watched a little bit of TV. Reporter: Her roommate leaves first, at 7:00 A.M. Christy would usually leave shortly after, by 7:45. But on this morning, she did not. In the next 45 minutes, something unspeakable would happen. I called her apartment about five times. Nothing. Reporter: Over at Christy's school, principal Goodman gets worried when she doesn't show up to her classroom. I called her mother, and I said, "Have you heard from Christy?" The phone rang. My mom was upstairs. She came downstairs and she said, "Christy didn't show up for work." She was worried, I was worried. And I said, "I'll tell you what. I'll drive down, and I'll probably end up changing her tire on the car." So I started driving. Her mother had given me her address. The farther I went, I did not see her, and then I started to panic. I pull up. Her car was parked there and I knew something was wrong. And the door was cracked open. So I'm yelling, "Christy! Christy! Christy!" Reporter: When he walks up, he's horrified by the scene in the living room. I told the police what I saw, but I've never told anybody else what I walked in on. I was at home when I got the call. There's a young woman who was found murdered in her apartment. Reporter: Joseph madenspacher is the Lancaster district attorney in 1992. I said, "I'll be there in 15 minutes." And we kept calling and calling and calling, and finally when somebody answered her phone at her apartment, they acknowledged themselves as being someone from law enforcement and that there's been an accident and she passed. Reporter: What was your reaction when you heard that? Devastated. Reporter: Officers begin to piece together what has just taken place. A horrific scene. Christy dead on the floor, her head beaten, her jaw broken. She had been raped and strangled. I struggled for years with this. Screaming, nightmares. Reporter: She is still wearing her coat and gloves. It's not a great leap of faith to say she was going out the door. Reporter: It is immediately clear to investigators that Christy was in a violent struggle for her life. Her footprint was found on the top of the door, suggesting that she had perhaps been lifted up and that her foot would've hit at that height. We found scuff marks just inside the foyer area. I saw a cutting board. It was in the living room. Which seemed relatively strange to me. Initially, what is believed is that she may have grabbed the cutting board as a way to defend herself and then the suspect used that on her. Reporter: In that scene of destruction, police are able to collect multiple samples of the killer's DNA. And those Christmas presents she had so meticulously wrapped the night before, are now strewn about the apartment. That has always, always, always haunted me. That there was her body, and close to it were these books that she had taken the time and put the thought into writing and for her kids. The cause of death has been listed as strangulation. Reporter: At Christy's school, a classroom full of students is wondering why their teacher never showed up. Assistant superintendent Bob wildasin is there. We just knew that she was dead, that Harry Goodman was the one who discovered her. But it was just -- everyone was in shock about it. Reporter: When 12-year-old Christina butler gets off the bus that afternoon, her mother is waiting to break the news. It was just almost incomprehensible to us at that time. We didn't understand the magnitude of it. We knew she was gone and that was awful. But we couldn't grasp just how violent and scary it was at the time. Who could this person be and why would this person do this to her? Because she was just someone that everyone loved.
This transcript has been automatically generated and may not be 100% accurate.