The murderer apparently then used the metal screen to dispose of Natalie's head. "The theory is that he carried her head on that and basically rolled it down the screen to where it ended up," Ainsworth says.
Enselma and Patricia Mirabal arrived at Matthew's apartment by mid-afternoon, then accompanied Matthew and Natalie's brother, Nehemiah, to the police station for questioning. They had not yet been told that Natalie had been found.
"When we walked out [of the apartment], we were going to the car, and I had a picture of Natalie on the sun visor," Enselma says. "I wanted to look at it and keep her there. But when Matthew saw that picture, he got mad. He got the picture and folded it. He did not want to see it.
"It sort of grabbed me. I was still wondering if maybe they had fought. As we were driving out, he said, 'Enselma, I'm sorry. I'm really sorry. My God. She was your daughter.' He said, 'She was a very stubborn person.'
"And I thought, my God, he's talking in the past tense."
It was about 8 p.m. when police broke the news of Natalie's death to the Mirabal and Vasquez families and to the church members who waited at the police department.
Investigators watched Matthew closely for a reaction.
"When we told him she was dead," Ainsworth says, "he said, 'I don't know what to do. This has never happened to me before.'"
Enselma recalls an equally odd response from her son-in-law.
"He said, 'Oh, my God. I'm only 21, and my wife is dead.' He never said he was going to miss her."
Soon thereafter, at the urging of Troy's father, Matthew obtained an attorney and stopped cooperating with police.
But it was already too late. Matthew had granted permission for detectives to search his home and Natalie's car.
After a thorough inspection of the car, investigators found a pair of dark brown gloves tucked between the passenger seat and the console. The gloves had blood on them. The left glove had a small slit on one side as if the person wearing them had been cut.
Police also found a pair of bloody pants in the trunk.
At Matthew's apartment, police found evidence of a possible motive: a $250,000 insurance policy on Natalie's life. Matthew was listed as the beneficiary.
Another key piece of evidence turned up at Matthew's workplace. Ainsworth found a Wal-Mart bag containing the hang tag from a pair of brown jersey gloves, the same brand that was found in Natalie's car. Matthew's fingerprints were on the bag.
Within days, Natalie's purse, driver's license and other evidence would be found tossed alongside a highway between Longmont and Boulder. Natalie's wallet still contained the $20 her husband said she was carrying when she disappeared. The only personal items that remained unaccounted for were her car keys and her checkbook.
Robbery was ruled out as a motive in her killing, as was sexual assault.
There was still a possibility that Natalie was the victim of a carjacking gone wrong, but the chances of that motive plummeted to almost zero when police matched tire tracks found in Lefthand Canyon to the tires on Natalie's car.
Carjackers, police said, would not be so kind as to return Natalie's car to the same place they'd found it. Matthew, though, would want to return the car to Safeway, which was within easy walking distance of his apartment.
And then there was the matter of the "scuff marks" on the passenger side of Natalie's car.
The trail and turnaround leading to where Natalie's body was found is lined with trees and bushes on the right side. A car driving down the trail too close to the trees would be scratched on the right passenger side.
"Matthew is blind in his right eye," Ainsworth says. "The car got scraped going down. On the way back up, the trees would be on his left. He can see out of his left. That's why there's no scratches on the [driver's] side."
Investigators made no secret of the fact that they believed Matthew had killed his wife.
"Detective Ainsworth called my house one day, and I said, 'I don't believe he done it,'" Troy Hancock says. "I will never be convinced that boy done that. And he said, 'I got all the proof I need.' He said, 'You don't care about Natalie.' He started telling me what [the murderer] had done to her, rolling her down the side of the mountain like a bowling ball.