At another point, he told van der Eem, "I tried to shake her. … I was shaking the bitch. I was like, 'What is wrong with you man?' I almost wanted to cry.
"Why does this s*** have to happen to me?" he asked.
In a voice seemingly devoid of emotion, van der Sloot said he turned to a friend of his.
"So I went and called the guy," he said. "I didn't call him on my cell. I walked over to a pay phone and I called him. And I told him, 'Well, this is what happened. Come, come, come help me. And please don't call the police.' He says, 'No I won't call the police. I'm coming to you now. And, he came there."
Asked how he knew Holloway was dead, van der Sloot said he "just knew it."
Van der Sloot said that he had known the unnamed friend since childhood and that "if I can ever do anything for him … I'd give my life for him.''
He went on to say that he'd take the man's name "to my grave,'' but a couple of days later identified him by his first name -- Daury.
After several conversations over a number of days, in which van der Sloot repeatedly talks about Holloway's disappearance, he told van der Eem, "It's a relief, really. … I've never told anyone [what happened to Holloway] in my life."
Finally, he insisted to van der Eem, "I'm putting it away and for me it's finished. Case closed."
When van der Eem replied that "you've got it off your chest'' and "it'll be alright man,'' van der Sloot turned to van der Eem and told him, "I'm being honest with you, Patrick.
"The two people I most trust in this … more than anyone, are that person and you."
Van der Eem, who grew up in the Antilles, said he decided to try to gain van der Sloot's trust out of anger that the young man's alleged crime had done so much damage to the reputation of the island of Aruba and the Netherlands. He said he combined his passion for information about the case with a false bravado to gain the trust of a man he believed carried a dark secret.
But in truth, he said, he was dying inside. At several points during his interview with ABC News, van der Eem became visibly distraught.
When Dutch prosecutors released van der Sloot in December and announced they had essentially closed the case for lack of evidence, van der Eem said he thought it was time to step up his own personal investigation.
It wasn't until that point that van der Eem said he felt close enough to van der Sloot to begin questioning him about the Holloway disappearance.
"The case is closed,'' van der Eem said he told van der Sloot, "and now, you know, if you want to tell me something, and, you know, I don't mind anymore."
"You know how much hurt I had saying those words -- 'I don't mind'?" van der Eem told ABC News, growing emotional.
"I definitely DO mind,'' he said.
"Why did I want this? It's obvious. Everybody was looking for the truth for [Holloway's] mother,'' he said. "I'm a father. I have two children, a girl six years old and a boy two years old."
He said there were times when he almost lost control of his emotions as he coolly played the part of a criminal.
"You know, I felt sometimes I had to cry, but I had to keep it in, you know? But as soon as he['d] get out of my car, my tears were coming."
Van der Eem said he never once felt he was betraying van der Sloot.
"No!'' he insisted adamantly to ABC News. "YOU betrayed MY country, and YOU betrayed the whole world, Joran. This is YOUR punishment."