Transcript for Man on Trial in Wife's Killing 7 Years After Her Death
to the suburban seattle man on trial for the murder of his wife more than seven years after her death. The victim's family is hoping they will finally get justice. Abc's neal karlinsky has that story. Reporter: In a seattle courtroom monday, a mother unflinchingly took on her daughter's alleged murderer. The same man she once called family. I just said, he murdered my daughter. I had cried my brains out every day for seven years. If he can't take being confronted by a 72-year-old woman, well, I'm sorry. But it's not much of a man if he can't handle that. Reporter: Nicole pietz vanished from home in 2006. At the time, her husbanden, david pietz, was among those talking to her reporters. Trying to focus on what we can do to be finding her so that you don't let your mind go to bad places. Reporter: Her body was later found in a wooded area, strangled. Police were interested in david as a suspect early on. They say he was unhappy with his marriage, frustrated with his job and having affairs. But it would be six, long years before they would arrest him, claiming to have built a case on circumstantial evidence and dna. Defense attorneys call the case flimsy, without a single eyewitness to a crime. It's not based on any direct evidence. And it's not going to show that david pietz took nicole's life. Reporter: Prosecutors say the case will take time to prove. Just as they say david was methodical in covering up the crime. Nicole's brother testified about her daughter's funeral and something she says david told her. He put his arms around me and said, I didn't think you'd take it so hard. Reporter: David pietz celebrated his 36th birthday in court monday. He's pleaded not guilty. For "good morning america," neal karlinsky, abc news, seattle. We're going to bring in abc's chief legal affairs anchor, dan abrams. And explain why it took so long to bring it to trial. They didn't think they had enough evidence until recently. Two things have happened, with regard to new technology. With regard to cell phones and with regard to dna. They've been able to better pinpoint where a crucial phone call was made that authorities say is incriminating. And with regard to dna evidence, they say they can link him to her car in a way they might not have been able to do previously. New technology has helped them confirm what their suspicions. They've been suspicious of him since very early on in the investigation. So, what you said helps. But the length of time, does that affect the case, though, in any kind of way? It's not helpful. You don't want to wait six or seven years. Memories start to fade. People switch jobs. Evidence is lost. There have been a lot of cases where it takes some time. This is not an easy case. They believe you have to put the puzzle together, to convict here. It's not a single piece of evidence. But of all the pieces of evidence, the one that struck me the most was the one that when her body was found, she was still wearing a dental retainer. Why is that so important? His account is that he sees her asleep at midnight. And that's the last time he sees her. Theoretically someone abducted her. And abducted her with a dental retainer. It's a crucial piece of evidence to say, it wasn't a stranger. It was him. Dan, thanks so much. Let's turn to the latest adventure for prince harry.
This transcript has been automatically generated and may not be 100% accurate.