Fifteen-year-old Katie Hamlin's nude and partially burned body was found on July 2, 2002, along the famous Cherokee Trail of Tears in Georgia's Appalachian Mountains.
For two-and-a-half years, the murder went unsolved, and police became desperate for a break in the case.
Roberto Rocha, a 20-year-old landscaper and the son of a minister, became a suspect in the crime. Rocha was a schoolmate of Hamlin's, and it seemed he had some kind of relationship with the young girl -- his number was found in her cell phone's speed dial.
Rocha went to the police voluntarily to be questioned. After all, he had an airtight alibi: He's been out of the country, in Brazil, the day Hamlin was killed.
During the questioning, police accused Rocha of killing Hamlin, which he vehemently denied -- at first. But a rare look inside the interrogation room shows how suspects can become confused, frightened and disoriented, and sometimes confess to things they didn't do.
"I didn't kill nobody, man. What are you talking about?" Rocha said during the police interrogation.
The police sometimes stretch the truth about evidence, which happened in this case. "I got three witnesses saw your truck," a cop told Rocha, who said he would submit to a lie detector test.
The police changed tactics and began to threaten Rocha.
"You better start telling the truth, or I'm going to lock your damn ass up!" said a policeman. "You don't know what we know. You think we just picked you out of the blue? Now start telling the truth!"
Rocha had never been arrested, and according to his attorney, Brian Steel, he also has a low IQ, which made him particularly vulnerable to suggestion. "The child is 20 years old with a 12-year-old's mind," said Steel.
The police continued to challenge Rocha, acting as if his presence at the crime scene was fact. After more than two hours, Rocha said he became confused and exhausted. He and his attorney said that police told Rocha if he went along with them, he could go home.
"Roberto Rocha just cracked and said, fine, I'll tell you what you want to know," said Steel.
But from the start, Rocha had trouble with key details of the case, such as where Hamlin's body was found. But the police "helped" him with that. One officer drew a map and said: "There's the bridge. You were there. ... Here's where you were parked."
"OK, I parked there," Rocha said on the videotape.
Steven Drizin, an attorney who specializes in false confessions, watched Rocha's interrogation.
"Drawing the map is like the cardinal sin of interrogation," Drizin said. "If you feed him those details, there's no way to know whether or not he's simply agreeing with what you're saying or he was there and he knows those facts."
Drizin said that Rocha was unable to provide the most basic details of the case, and when he did, he made mistakes. Rocha told police it was chilly outside, even though it was July, and he said it was hard to see because there were so many trees, when in fact, there were no trees in the area.
"He's trying to come up with the story. He's making this stuff up as he goes," Drizin said.
Capt. Ron Hunton, who questioned Rocha that night, said an interrogation is an emotional battlefield.