One of them, Joran van der Sloot, a Dutch youth who has acknowledged spending the evening with Natalee Holloway before her disappearance but denied any wrongdoing, left the island to attend college in Holland.
Van der Sloot is allowed to leave the Caribbean island but must remain in Dutch territory under terms of his release.
Prime Minister Nelson Oduber, who has previously said Aruban authorities made mistakes in the early part of the Holloway investigation, added that he could appreciate the "dismay" of the missing teen's mother.
"But, the case is not concluded. And we will continue to demand that the search for answers into what happened to Natalee will not cease," Oduber said in a statement released Monday.
The remarks from the prime minister, who is running for re-election this month, are the first since the release Saturday of van der Sloot, 18, and two Surinamese brothers.
Van der Sloot's mother, Anita, pleaded for the media to leave him alone.
"He's a good boy. It's enough," she told The Associated Press. She also expressed sympathy for Holloway's family in the telephone interview.
"I pray for Natalee and the Holloway-Twitty family and I'm still convinced she is alive," she said.
Holloway's mother, Beth Holloway Twitty, left Aruba for her home in Mountain Brook, Ala. on Sunday, saying she had "exhausted all my avenues" after pressuring authorities since shortly after the teen disappeared on the final day of a high school graduation trip to the Dutch Caribbean island.
Holloway was last seen leaving a bar with van der Sloot and the two brothers, Satish and Deepak Kalpoe early on May 30. The three young men were released on condition they remain available to police for questioning.