Van der Eem said he found it painfully ironic that van der Sloot was able to go home and fall asleep the night he allegedly arranged for Holloway's body to be disposed of, since he said he himself had trouble sleeping.
"I had a lot of days I couldn't even sleep! And I was harming nobody. But with the information I had in my head? … Now, the release comes … my head is going to get empty talking to you, showing the world what happened."
Van der Eem said that throughout his investigation, his concern was less with gathering legally-admissible evidence than with cracking the case, for Holloway's family and for the Dutch and Aruban people.
"We're going to punish him,'' van der Eem said. "His punishment will be very simple, sir. He's gonna get a lifetime sentence. Maybe not in jail. But I would not want to be Joran van der Sloot after everybody in the world sees these" undercover tapes. … There ain't no rock in this world you can crawl under."
Van der Eem said he doesn't regret halting the investigation and not trying to take it any further than he and de Vries did. He said he did all he could, emotionally, and that he was leaving his undercover persona behind and getting on with his life.
"You said it's like a chess game,'' Cuomo asked him.
"Absolutely,'' van der Eem replied. "But I'm finished. It's checkmate."
For Holloway's mother, Beth Twitty, the new information is both a blessing and a curse, she told ABC News.
"It's over,'' she told ABC News. "I mean it. It's the end … this is the end for me. It's what I have prayed for for two and half years. I've just prayed for an answer, and that's all I've ever wanted. I've just wanted an answer to what happened."
Still, she said, "it makes you sick.
"How can [an individual] have such disregard or disrespect for a person's another person's life … and only be concerned about your own existence."
Later in the interview, she said, "Dear God! Joran could have called, he could have called an ambulance. He's not an EMT [emergency medical technician]. He's not a, a doctor! You know? He's not a, he's not anyone that could, could make a decision on my daughter's condition.
"And he chose to be that person himself, to decide, you know, whether he's going to seek medical help for Natalee with her laying there in his presence -- or is he gonna make the decision to dispose of her body? I mean, dear God! He did! And even though he didn't know if she was alive or not … dear God."
De Vries, the crime reporter, took his information to Aruban prosecutors last week and almost immediately, authorities on the island announced a reopening of the investigation, which just last month they had said would be closed due to lack of evidence.
"The office of the Public Prosecutor of Aruba has intensified its investigation of the case of Natalee Holloway due to recently received information,'' a press released issued last Thursday said. "This information may shed a new light on the mode of which Natalee Holloway has died and the method by which her body disappeared. … The Aruban Police Corps has continued the investigation of the case despite the formal discontinuation of the prosecution of the suspects of the day, in December 2007.''
As part of deal with defense attorneys for van der Sloot and two other local men, prosecutors had said they would discontinue the nearly three-year investigation by year's end if they couldn't gather enough evidence to bring a case.
The transcripts of van der Sloot's conversations with van der Eem appear to exonerate Deepak and Satish Kalpoe, two Surinamese men who live on the island with their parents.
Neither of the brothers could be reached on Sunday. A man who answered Satish Kalpoe's cell phone and said he was Satish's father declined comment, as did a woman who answered Deepak's cell phone.
Despite what appears to be damning new evidence, Aruban attorneys say that prosecutors still face an uphill battle in prosecuting van der Sloot, even if the tapes were ruled admissible in court.
ABC News' Andrea Beaumont contributed to this report.