"Experience in law enforcement just tells us that people can not keep this kind of secret forever," says the head of the unit, Dan Westin. "They've got to tell somebody."
From the start, Smith was their only suspect. "It's a very poor alibi to say that his wife ran off with another man, leaving behind her car, her rings, cash, a check from work, credit cards and all that sort of thing," Westin says.
The unit did 120 separate interviews, trying to find a new lead. At many of the interviews, detectives played the tape made by Detective Dyloff, when Smith seemed ready to admit manslaughter.
As investigators played the tape for Smith's ex-girlfriend Judy, she told them what Smith had told her: When Khris had come into the bathroom with a gun, he had disarmed her and shot her.
Detectives uncovered other evidence, too. They found that the letter that Smith had shown his neighbors had in fact been written years before Khris had been killed.
Despite these new findings, the cold case unit still didn't have sufficient physical evidence to charge Smith with murder. They went back to the remodeled bathroom, taking it apart piece by piece. They found bloodstains.
But tests couldn't determine whose blood had been found. The detectives bluffed and put out a news release that they had found evidence at the crime scene. They talked to Smith's parents, and Candace, trying to persuade them to get him to confess.
When police interviewed Candace and Smith's parents, they refused to listen to the tape of Smith's near confession. Then, in late October 1998, detectives for two hours met alone with Smith's father.
He called his son and told him that he had heard the tape, and that detectives were coming to Florida to interview him.
In early December, the unit drove to Florida. Investigators wanted a confession. It was a long shot. They had no arrest warrant, no physical evidence; Smith was not obligated to speak with them.
First investigators located Smith at his job. When he left to run errands, they tailed him. Smith stopped at the post office. It so happened that his lawyer had sent him a newspaper article about the continuing search for Khristine's killer.
The timing was uncanny. As it turned out, when Smith walked outside, there was Detective Westin waiting for him. Smith agreed to talk to Westin at his home. After several hours of conversation, Smith seemed ready to confess, Westin says.
"He started saying that it's just too hard to say the words," Westin recalls. "And so I just started moving the questioning down into very little tiny steps."
Smith said that on the morning in question, his wife put their daughter on the school bus and then returned home. Smith told police he and Khris had started arguing. She threatened to leave with their daughter Candace.
"And I told her that was fine; she was welcome to leave, but she wasn't taking Candace anyplace," he said.
"She turned her back to reach for a towel, and I said 'I love you. What's wrong?' and she turned around, and she says, 'I hate you.' And she spit in my face. After that I walked out of the room. And I retrieved the gun, and I came back, and I shot her." He shot her twice in the head, he said.
Then Smith put his wife in a storage barrel, took it downstairs and put it in his truck, in the garage. When Candace came home from school, he drove her to Ohio to stay with his parents. After dropping off Candace, Smith drove south for about six hours, before turning around and heading back to Kalamazoo.
He borrowed a boat from a friend, went to Lake Erie, traveled out about nine miles, and threw the barrel over the side of the boat.
Smith killed Khris in a rage over her numerous affairs, he said, adding that now he wishes he had divorced her rather than murdered her.
"No matter what he's done, he's still our son," says father Dick Smith, crying.
Kitty was shocked, too: "We were building a beautiful future together, and it's just been ripped away."
According to Smith, it wasn't just his wife's alleged affairs that led to his rage. She was selfish and mean, he says.
To avoid a trial, Smith pleaded guilty to second-degree murder. As part of his plea bargain, Smith agreed to help detectives find her body. But during a day of searching on Lake Erie, they found nothing.
Hoping to persuade the judge to give him a light sentence, Smith wrote him a letter.
It stated, in part: "Although all the infidelities and affairs and mental abuse are no way an excuse for what happened, I was mentally and emotionally pushed to limits that no one should have to endure. I'm not a violent person, never have been, and never will be."
Westin doesn't buy Smith's remorse or his claims about Khristine's affairs. Throughout all the interviews, his unit found no evidence that she was unfaithful, he says.
The judge apparently agreed, because earlier this year he sentenced Smith to 35 to 70 years in prison. His first chance for parole will be in 27 years.
Police have given up looking for Khristine's body. The only headstone to mark her grave is an anchored buoy.
Produced by David Kohn;