After reexamining Leah's bloody shoes and how her body was dumped, Walters labeled Leah's killer a "power assertive crime type."
"Power assertive is that muscle flexing, tectonic kind of braggart who thinks he's John Wayne, who wants to be a bigger man than what he is," Walters said. "The end goal was to get [Leah] dead and to get her dead in the most efficient way."
With this fresh perspective on the case, police were even more convinced that their prime suspect from the beginning, Leah's boyfriend, Nick McGuffin, was her killer.
But without a DNA match or an eyewitness, they needed enough evidence to build a circumstantial case that would hold up in court. They again reviewed integration tapes of McGuffin's account of what happened the night Leah disappeared.
McGuffin claimed he went to Leah's friend Cherie Mitchell's house to look for her around 9 p.m., but Leah already had stormed off. Then, he said he drove around for hours in his 1967 Ford Mustang looking for her.
Police said they had several witnesses who saw McGuffin acting strangely that night, including Mitchell, who said he showed up at her house a second time at around 10 p.m.
"He was definitely, you know, jumpy, talking fast," she said. "It was definitely odd."
Police also noticed that McGuffin seemed convinced that the worst had happened to Leah when they first interviewed him in 2000, and that he kept reverting back to past tense in his written statements.
"He tells us that Cherie was, was, her best friend, and the question is: How does he know that Cherie and Leah are no longer best friends?" said Mark Mclish, a handwriting expert who specializes in statement analysis. "The answer is 'cause he knows that at this point in time, Leah's dead."
Police then reexamined McGuffin's Mustang, even though it had already been sprayed with a chemical called luminal to test for the presence of blood during the initial investigation in 2000.
"There was nothing in there," said police chief Mark Dannels. "It had been cleaned. It had been wiped."
During the second round of searching, police got a huge break in the case.
Another witness, Kristen Steinoff, was questioned, and told police that McGuffin had stopped by her house around midnight on the night of Leah's disappearance. She said she and McGuffin did drugs, and when he tried to have sex with her, she refused. He also barrowed her car that night -- a Kia.
"Here's a guy that's worried about his girlfriend, that he's frantic about her ... but he's making a move on this girl," Dannels said.
The Kia had been sold, but detectives traced it back to its new owner in northern Idaho. After searching it, they found it, too, had been thoroughly cleaned, with air fresheners placed in the passenger side compartment and the trunk.
Steinoff was bought in again for questioning. She insisted she knew nothing about what happened to Leah, but then revealed to police that she had seen McGuffin twice that night. When he came around a second time, he was wearing different clothes and had threatened her.
"He started saying to keep my mouth shut," she said. "Then, I kind of figured that he did have something to do with it because of the way he was acting."