ORANJESTAD, Aruba (CNN) -- In an Internet chat shortly after the May 30, 2005, disappearance of Natalee Holloway on Aruba, one of the three main suspects in the case said the Alabama teenager was dead, the island's chief public prosecutor told CNN on Thursday.
Natalee Holloway disappeared while on vacation in Aruba with classmates in 2005.
The chat, retrieved from a computer hard disk, was among new evidence prosecutors used to justify re-arresting the three in November, Hans Mos said.
New technology that was not available to authorities in 2005 was utilized to find that chat and more between two of the three suspects as well as others, he said.
Judges, however, ruled the new evidence was not enough to keep the suspects -- Joran van der Sloot and brothers Deepak and Satish Kalpoe -- behind bars. Mos' office said Tuesday they will not prosecute the three in Holloway's disappearance.
But his office also said the case is not closed, rather that it has now entered "a new phase" with four Aruba detectives still working on it, looking for new evidence. Watch a report on the case »
In the chat, Mos told CNN's Susan Candiotti, one of the suspects said, "The fact that she's dead is not good," referring to Holloway.
Other chats occurring before May 30 were also found, in which the suspects discussed "picking up American girls and what they plan to do with them," Mos said. Such chats gave authorities an idea of how the suspects operated, he said.
But, he said, authorities did not find any further discussion of Holloway's death or how she died. "If we had that, we would have been much further [along] than we are now," Mos said.
Other evidence against the three included two new witness statements. In one, a female friend told authorities that one suspect called her about five hours after Holloway was last seen leaving an Oranjestad, Aruba, nightclub with van der Sloot and the Kalpoes.
The female friend said that she could tell during the conversation that something was wrong, Mos said. When she asked about it, the suspect -- whom Mos did not name -- told her that "he didn't want to cause her any trouble, and that what had happened couldn't be discussed over the phone," he said.
Police wanted to ask the suspect what he meant by that statement, he said, but after their rearrest, all three men exercised their right to remain silent and refused to speak to authorities. See a timeline of how the case has developed »
A second witness statement came from a teacher who said that another one of the suspects exhibited "very peculiar behavior" the day after Holloway's disappearance, including making or receiving a lot of telephone calls, Mos said.
A fourth piece of new evidence came when authorities bugged the Kalpoe home in June and picked up a conversation about what happened that night, he said, but did not elaborate.
Holloway, 18, disappeared while visiting Aruba with about 100 classmates celebrating their graduation from Mountain Brook High School in suburban Birmingham, Alabama, and was last seen leaving the nightclub with the three youths. She failed to show up for her flight home the following day, and her packed bags were found in her hotel room.
All three suspects were arrested and released in the case in 2005. They were rearrested November 21, with authorities citing new and incriminating evidence against them.
In freeing the Kalpoes from jail November 30, judges from Aruba's Court of Appeal wrote that there was no evidence that Holloway died as a result of a violent crime against her or that the suspects were involved in such a crime. Using similar reasoning, a judge released van der Sloot a week later.
All three have maintained their innocence in Holloway's disappearance. The Kalpoes have told police they dropped Holloway and van der Sloot off near a lighthouse on the northern tip of the island after leaving the nightclub. Van der Sloot's mother, Anita, has said her son told her he was on the beach with Holloway but left her there because she wanted to stay.
What authorities needed, Mos said, was for at least one of the three to explain what happened that night. That's why, he said, his office went to the expense of extraditing van der Sloot from the Netherlands, where he is attending college, after rearresting him in November -- out of hopes that he might talk.
"You never know whether a person two years later will, yes or no, open up," he said.
Mos said that when the three youths were rearrested, he asked an attorney for Holloway's divorced parents, Beth and Dave Holloway, to tell them not to get their hopes up too high, as this was not "the final breakthrough" in the case.
And on December 1, Mos said, he and others in his office had "a very good talk" with the Holloways.
"Sometimes I got the impression that we aren't on the same side," he said. "That sort of disturbed me, and I think they should know that we are just as much dedicated to solving this case as they want us to be, and I cannot come up with the results. I wish I had. I feel very sorry."
He acknowledged the new evidence against the three was circumstantial, and rearresting them may have been a long shot, but "we had to give it a shot.
"I would never have forgiven myself," he said, and never would have been able to answer the question "Why didn't you even try?" given the new evidence.
"And that's exactly what we did. I'd rather give it a try and not succeed than not give it a try at all. We gave it everything we got. We cannot torture these three guys and make them tell what happened."
He said his office remains determined to find out the truth. "We believe justice will prevail one day, but we cannot force that right now."
Although Mos' decision not to prosecute the case means that under Aruban law, the three cannot legally be considered suspects, Mos said they remain persons of interest.
In interviews, he said, van der Sloot and his father have indicated they know more than previously said about what happened to Holloway, but are not willing to divulge it, giving authorities "reason to believe that their last and final story is simply not the complete story."
Authorities have found no indication that anyone else could have been involved in Holloway's disappearance -- but also have no evidence to show a crime was committed, or what crime that might have been, he said.
If Holloway's death was an accident, as some evidence suggests, Mos said he doesn't understand the need to cover it up -- or why someone didn't simply call 911 and report it the night it happened. "That's an indication there is more at hand than just an accident," he said, "but what it was, and who was involved, I don't have evidence."
Van der Sloot's American attorney, Joe Tacopina, has criticized Mos for suggesting his client was involved in Holloway's disappearance if he does not have evidence to back that up.
In response, Mos said that if van der Sloot were tried and acquitted, double jeopardy would attach and he never could be tried again. Just because he decided not to prosecute, he said, doesn't mean "there is not a file in which these three people are primary persons of interest."
Tacopina has declared his client is innocent. "That's quite funny," Mos said, "because he wasn't there on the 30th of May. Neither was I. He should ask his client." E-mail to a friend