Oranjestad, Aruba ? A main suspect in the disappearance of American teenager Natalee Holloway wrote in a chat session that she was dead – a key clue for investigators, but one that fell short of assuring a conviction in court, Aruba’s chief prosecutor said Thursday.

The prosecutor Hans Mos insisted his office has done its best to learn what happened to Holloway, an 18-year-old who went missing in this Caribbean island on May 30, 2005, and is believed to be dead.

Mos said he has done all he can to bring those responsible to justice.

“Given our sincere commitment to solving this case, we exhausted our toolbox,” he said at a news conference.

The Aruban prosecutors say they cannot prove a crime was committed without a body.

Mos said he understands the frustration of Holloway’s family, which has criticized Aruban law enforcement and their decision this week to dismiss the case against the three main suspects.

Attorney General Nico Jorg said the case against the three could be reopened if additional evidence surfaces. But if they were to go to trial now with virtually no hope of guilty verdicts, they would lose the opportunity to try them later if strong evidence emerges.

“After a final acquittal, it is legally impossible to reinstate a prosecution,” Jorg said in a statement. “(We are) hoping better times will arrive eventually.”

The family blames mistakes by Aruban investigators for bringing the case to a dead end after more than two years of searching for Holloway, who vanished during a vacation with her high school graduating class.

Mos refused to reveal which of the three suspects wrote the Internet chat message, but said its discovery contributed to the decision last month to rearrest the men.

Joran van der Sloot and brothers Deepak and Satish Kalpoe were subsequently released after they refused to speak to authorities, and the Aruba Public Prosecutor’s Office announced they would not be charged.

The three were seen leaving a bar with Holloway hours before she was due to board a flight home to Mountain Brook, Ala. Van der Sloot, who now attends college in the Netherlands, said he left Holloway alone on a beach that night. He and the Kalpoe brothers have denied any wrongdoing.

Mos said Internet messages between two of the three suspects discussed a “way of operating they had, of picking up American girls” on the Caribbean island, where American visitors enjoying the 18-year-old drinking age go from bars to nightclubs late into the night.

An attorney for van der Sloot said his client is innocent.

“There is absolutely no evidence against Joran,” attorney Joseph Tacopina told The Associated Press. “People were misled. As far as I’m concerned, the case is over.”

Ronald Wix, an attorney for the Kalpoe brothers, ridiculed what prosecutors described as new evidence.

“All they did was recycle old evidence and claim it was new evidence,” Wix told the AP, adding that his clients felt vindicated by the decision to drop the case.