Right now, let's get to the bizarre murder trial in georgia. Steve osunsami is covering this from atlanta. The defendant has spent ten years in jail for stalking this roommate, who they cross-examined... See More
Right now, let's get to the bizarre murder trial in georgia. Steve osunsami is covering this from atlanta. The defendant has spent ten years in jail for stalking this roommate, who they cross-examined yesterday. For ten years. You can imagine how upset she is him acting as his own attorney and grilling her on the witness stand. She moved into a friend who was murdered, before he went to jail. And now, after all these years, police have fingered him for that killing. It was a few days after you murdered carmen and stabbed nick. Reporter: Loretta spencer black, whose identity is being protected, facing down the man she helped put away for stalking her in 1994. I want to object. Completely unresponsible to my question. And has -- it's really inappropriate that you stalked me and harassed me and you're sitting here asking me questions and I have to answer your questions. That's hard for me. Reporter: He is now out prison and acting as his own attorney, on trial for his roommate's brutal murder. I would have done things differently. But I can't. I can't turn back time. I wanted to make it -- I wanted to make it stop. Just stop. I just wanted it to stop. Reporter: Black and baker met on a paintball team. And he became obsessed with her. Calling her at all hours. Showing up and refusing to leave. And breaking into her home. He was harassing her on the phone. Reporter: Her roommate, carmen smith, was found murdered in the home they shared in 1995. Smith's 5-year-old son was stabbed more than a dozen times and barely survived. I didn't realize this was going to turn into murder. If I would have known, I would have taken notes. Reporter: For years, investigators suspected baker killed smith in an act of revenge. But in 2009, they announced they finally got it. A dna test of hair found on smith's body, tied him to the murder. He pleaded not guilty. And the would-be lawyer told jurors he and blass were a couple. There's so many different things that happened that you did. I can't remember everything that you did. I spent my entire life just to erase everything. Reporter: We're expecting some really gripping testimony. That 5-year-old son who was stabbed so many times is now in HIS 20s, GEORGE. And is expected to tell his story on the witness stand any day now. What a moment that will be.
This transcript has been automatically generated and may not be 100% accurate.