"If I had had any idea that he did this horrible crime, I wouldn't represent him. It's just that simple," Powell told "48 Hours Mystery" correspondent Erin Moriarty.
"I've talked to a lot of defendants," Powell continued, "but after sitting there nose-to-nose with him… there was no doubt in my mind that he was telling the truth that he did not do it. He knew nothing whatsoever about it."
Authorities see it differently; they say that Moore killed Karen Tipton, a wife and mother from Decatur, Ala.
"We're not talking about a few years of my life. We're talking about my entire life - my right to breathe. They can't do this," said Daniel Wade Moore.
Moore has always said he wanted his day in court. And he got it.
"I didn't do it. I was nowhere near that house that day when that woman was murdered," he told Moriarty.
In fact, Moore received more days in court than he'd care to count.
"Time and again you get a little bit of hope only to have the carpet jerked right out from under you," he explained. "You can only take that so many times before you learn to quit hoping."
No one would blame Moore for giving up hope - especially after his first capital murder trial in 2002, when he was found guilty.
"My jaw hit the floor. It was just unbelievable," he said of hearing the verdict. "I mean it was just - I was in shock."
Moore wasn't the only one. Presiding Judge Glenn Thompson, who read over the jury's verdict moments before it was revealed in open court, could not believe his eyes.
"A former law partner saw my reaction. He said he saw the blood drain out of my face. He said I just turned white from the top down when I saw the verdicts," Thompson told Moriarty. "I was that surprised."
When asked why, the judge explained, "I didn't think the state had proven it… too many unanswered questions… it never got to a point of beyond a reasonable doubt."
Given Judge Thompson's reservations - "It didn't matter what I thought. The jury said he did it" - what he did next could be considered shocking.
When it came to Moore's sentencing, Thompson said he was required by law to consider the severity of the crime: Karen Tipton had been stabbed 28 times and her throat was cut.
"It was the most heinous crime that I think has been committed in this county ever," Thompson said. "No one deserves for their loved one to be butchered like that."
In accordance with the law, the judge imposed the maximum penalty: death.
"Death was the appropriate sentence," Thompson explained.
It's highly unusual for a judge to speak publicly about a case, but Judge Thompson granted "48 Hours" this interview.
"It's not that I wanted to sentence him to death, but I did."
But that guilty verdict was set aside and the state tried Moore again and then, yet again.
"I've seen maybe a fraction of one percent of cases end up lasting this long or having three trials. It's just really unheard of," said Powell.
How does a man get tried three times for the same murder? We'll explain, but first we need to go back to the afternoon of March 12, 1999.
Doctor David Tipton, a psychiatrist, was married to Karen, who was a 39-year-old housewife.
"She was in the prime of her life," Tipton said. "She was prettier than she'd ever been in her life."
Tipton, who was also 39, said he came home from work earlier than usual that day to go to the theatre. When he walked from the garage into the house, he noticed the deadbolt on the door was not locked. Tipton went into the foyer to hang up his coat.
"I still think Karen's upstairs. This is a big house," he explained. "I did call for her… She should have been there with the children. At that point saw a drop of blood. One small drop of blood on the foyer, on the tile. The next thing I saw was more blood in the foyer, toward the door. And I walked up the stairs and was the most surprised person on the face of the earth to get to the top and find a dead body there that looked somewhat like Karen."
Karen's nude body was lying at the top of the stairs.
Tipton called 911: My name is David Tipton. I'm at 2330 Chapel Hill Road and my wife has been killed. There's blood everywhere and I'm really concerned about my children.
Investigators began searching for clues as officers tracked down the Tipton children, who were still at school where they had never been picked up.
"The worst day of my life was about a week after the murder," Tipton explained. "And that was when Catherine, then 3 years old, asked me when Mommy was coming back from heaven. That was the worst single moment that I could ever imagine, because that was a beautiful, innocent little child who had been told that her Mommy had gone to heaven, and a week later she was wanting to know when she came back."
The crime scene was puzzling. Tipton reported that Karen's purse and some jewelry were missing, but her diamond ring was still on her finger.
At the time of the murder, which he described as "a shockingly brutal homicide," Ken Collier was chief of investigations for the Decatur Police Department; today, he is police chief.
Chief Collier said there was no evidence of forced entry at the Tipton home.
"In a case where a woman is found in her own home, murdered in the middle of the day, who is usually the first suspect? Who do you look at first?" Moriarty asked Collier.
"You'd start, normally, with either the husband or wife," he replied.
"Even from the beginning, I realized that I had to be a suspect. Because, I was the first on the scene and the husband. I knew that," said Tipton.
Police believed Karen was murdered sometime between 1 p.m. - after a phone call to a friend - and 2:30 p.m., when she usually picked up the kids from school. Dr. Tipton's office manager told police that he left his office in neighboring Huntsville at 3:30 p.m.
"He had an alibi that we were able, at least that same day, to partially substantiate," said Collier.
It was enough for police to allow Dr. Tipton - the natural suspect by his own admission - to go back into his home the night of the murder.
"But if they let him back in the house, the crime scene, they didn't consider him a suspect who might try to destroy any kind of evidence?" Moriarty asked Collier.
"Well, I can't get into their heads, but that's a reasonable statement," he replied. Collier said Tipton didn't have any injuries or anything to indicate to officers that he had just been involved in a brutal murder.
Police needed some answers. There was no murder weapon or fingerprints found at the scene. But there was pressure to make an arrest.
"High profile. Rich doctor's wife. Beautiful lady. Brutally slain. Don't you think there was a little bit of pressure on the police department? I think there was a lot of pressure on them. They had to have something," said Powell.
Cops got nowhere for a month until suddenly they got a lucky break. Moore's Uncle Sparky went to police and told them that Daniel had said something alarming.
"He said, 'You know the Tipton murder? The doctor's wife that was murdered on Chapel Hill road?' And I said, 'Yeah.' And he says, 'Well, I was there.'"