Transcript for Chris McCowen goes on trial for Christa Worthington's murder: Part 7
screen. I have the greatest job in the world. Detectives arrested -- Much needed relief for residents. For cape cod this was the trial of the century. This is a small town in Massachusetts. It hadn't had a first-degree murder case in 30 years. The parking lot is chock-a-block full. Satellite TV trucks, reporters all over the place with cell phones, computers. The courtroom and the Barnstable court house is this sort of antique space, and hanging from the ceiling is this beautiful silver codfish. As if everything that goes on here has this cod god above it. 33 year old Christopher Mccowen was arraigned today in Barnstable superior court. The prosecution claiming Mccowen's DNA links him to the violent stabbing of fashion writer Christa Worthington. Robert Walsh is the lead prosecutor, and he's going to make an argument that they can prove beyond a reasonable doubt that Chris Mccowen raped and murdered Christa Worthington. Please raise your right hand. The first witness is Tim Arnold. He was the ex-boyfriend. He's the one who found her body. There was blood around her head. Her knee was up in the air. Were her legs together or spread apart, sir? Somewhat spread apart. Reporter: It's not just that she was stabbed to death. She was also horribly beaten, and there's bruises all over her body. The photos were very graphic. I think those photos helped us to get the reality of the crime scene, to get the reality of a murder was committed. The defendant was completely indifferent to her suffering, and that's based on the statement that you'll hear that he made. A major component of this case was Christopher Mcgowan's statement given to the police during a very long interrogation. The prosecution relied upon it. Christopher mason, the lead detective from the Massachusetts state police, was a professional police officer who presented very well, and he was credible. And did you have occasion to interview a Christopher Mccowen? Yes, I did. The first two times that Mccowen was questioned by the authorities, he basically denied knowing her, but then they hand him the DNA report. And everything changes. And I informed him that the report from the state police crime lab concluded that it was his DNA on the body of Christa Worthington. All right. And after you showed him that report, slid it across the table to him, what did he do next, sir? Mr. Mccowen then stated, it could have been me. It could have been me. It could have been me. So Mccowan is saying it could have been me who had sex with Christa, because it was his DNA. Some of the strongest evidence against Christopher Mccowen is his statement. I mean, he denies knowing her, and then his semen is inside her. I mean, hello? And then his statement gets more and more incriminating. In his statement to police, Chris Mccowan first says that Christa asked him to help dispose of a Christmas tree. Mr. Mccowen explained to me that he had had a discussion with Christa Worthington that evening in that house about getting rid of the Christmas tree. That Friday night, is that correct? That's correct. Mccowen's statement to the police progressed to the point where he admitted that he had consensual sex with Christa Worthington on the living room floor. His response was, I The Out of her. I don't know. Is that a direct quote, sir? Yes, it is. Reporter: He changes the story, and introduces another person, a friend of his that he would socialize with. He goes on to say, I wasn't the only one there. Jeremy Frazier and I went up there. Jeremy Frazier becomes a player in this case. He's young, under 21, knows Chris Mccowan because they apparently hang out and run in the same circles. Jeremy Frazier admits that he was with Chris Mccowen earlier in the night, the night that Christa Worthington was killed, and there's video in this bar where you can see them. Reporter: In his statement to police, Mccowen says that he and Frazier leave the juice bar and go to Christa's house. Mr. Mccowen stated that he gave Jeremy Frazier directions, and that Jeremy Frazier drove him -- drove them to Christa Worthington's residence. Mccowen claims that he asked Jeremy to drive him to Christa's so he could have sex. He didn't want to drive himself. He was afraid of getting busted for drunk driving. He was wasted. He then indicated to me that -- that Christa Worthington was startled to see us. He stated that he probably said something like, I'm tipsy. I just wanted to get some -- real quick. Mr. Mccowen informed me, she was cool with it. Mccowen's account was the he went up there, and he and Christa got it on and Jeremy meanwhile was taking her possessions. He indicated that following the sex, Christa Worthington confronted Jeremy Frazier about -- about what he was doing. He and Jeremy Frazier then left the residence, and that Christa Worthington followed them out. At which point, again this is the Mccowen account, Christa comes barreling out of the house and starts screaming at Frazier, you , you thief. I want me stuff back. What did he say, sir? He stated, Jeremy lost it, and I just followed suit. It was pandemonium. They get into a fight, which starts outside. They get into it in the driveway. He stated that Jeremy beat her. He beat her. He said, we put the boots to her. He said, I still can hear her hit the ground. She hit the ground hard. He states that Jeremy Frazier then dragged her under the arms and dragged her into the house. Frazier was beating on her, and he punched her in the face, and in the chest, and he said it was Frazier who took a knife, and stabbed Christa through the chest. I asked Mr. Mccowen, well, what would he say if the troopers in truro, and I determined that Jeremy Frazier was somewhere other than truro on that evening? And what was his response to that, please, sir? His response was, then it's all -- then it's all on me if Jeremy can account for his time. That was the final version that emerged from the six-hour interview. You have all of those versions, which was from, I did have sex with her, to being around, but wasn't involved in the homicide, to literally sounds like being in the same room when the homicide occurred. He changes the version, but he never puts a knife in his hand. He never vacillated from the fact that he never killed Christa Worthington. The defense said he cannot be trusted. The statement is not worth the paper it's written on. Led him to self confession. He was putty in their hand.
This transcript has been automatically generated and may not be 100% accurate.