Steve Gregory Croes, whom authorities earlier identified only by his initials, "S.G.C.," said he was contacted by police Thursday night and went to the station voluntarily to give a statement, according to the employer, Marcus Wiggins. Croes was arrested early Friday.
Croes also said he knew one of two Surinamese brothers being detained in the case because he went to the same Internet cafe, Wiggins said.
Croes was working as a disc jockey on the "Tattoo," a large tourist boat offering nightly dining, dancing and swimming, Wiggins said.
Wiggins said he had seen neither the Surinamese brothers, Deepak Kalpoe, 21, or Satish Kalpoe, 18, nor fellow detainee Joran van der Sloot, 17, the son of a justice official from Holland, aboard the boat. A brochure for the boat says patrons must be 18 or older.
"I've never had problems with him," Wiggins said of Croes. "He keeps to himself and shows up to work every day and does his job."
Wiggins said Croes had worked for the boat "for a period of time," but he could not say how long exactly.
Natalee's mother, Beth Holloway Twitty, told the Associated Press. "Whether or not he's involved with my daughter's disappearance, I can't wait to find out that answer."
Prosecutors have gone back to court to ask that van der Sloot and the Kalpoe brothers stay in jail. Under the law, a judge must review their case after 10 days and decide their status.
"The process allows for a period of time for the prosecutor to do the investigation. That can go well over 100 days," said local attorney Lincoln Gomez.
A judge was expected to rule as well Friday on another petition, from van der Sloot's father, Paul van der Sloot, to be able to visit his son in jail. None of the four detainees has been formally charged with a crime.
Authorities' announcement of Croe's arrest Friday came nearly three weeks after Holloway's disappearance in the early morning hours of May 30, the same day she was to return from a five-day trip with 124 other students celebrating their high graduation in Mountain Brook, Alabama.
"It's emotionally draining, it's physically draining,"told CBS News Early Show co-anchor Julie Chen. "Every day, we wake up, 'is today going to be the day? Please let us find Natalee.'"
On Thursday, Police Superintendent Jan van der Straaten told The Associated Press that authorities used a helicopter "to search for possible remains — but found nothing." He declined to say where the helicopter searched.
"I don't think they're going to find Natalee until these [first] three guys talk," said Robin Holloway. "They know they were the last ones to see her. And I firmly believe in my heart they know where Natalee is and just please tell us. They hold the answer.
Asked why it took investigators more than two weeks after Holloway's disappearance to search the van der Sloot home, Attorney General Caren Janssen said Thursday, "You have to build up an investigation. You can't just go in there like a cowboy, you have to give certain direction to investigators."
The Kalpoe brothers have told police that they and Joran were with Holloway and that she and the Dutch youth were petting in the back seat of their car. The detainees initially said they took Holloway to a beach on the northern part of the island then dropped her off at her Holiday Inn hotel, where they claimed she was approached by a security guard.
But Antonius "Mickey" John, a former hotel security guard released from custody on Sunday, told reporters that Deepak Kalpoe told him during a chat in jail that he and his brother actually dropped the young van der Sloot and Holloway off together near the Marriott, about 10 blocks north of the Holiday Inn. John said he passed the information on to police.
Kalpoe's lawyer would not comment on John's statement Wednesday, but said his client maintained his innocence.
Van der Straaten dismissed rumors that police may investigate coastal waters on the north side of the island known to have sharks. "Sure, we have shark places on the northern side, but they have nothing to do with the investigation," he said.