Oranjestad, Aruba ? Behavioral specialists on Tuesday questioned a young Dutch suspect in the disappearance of Natalee Holloway, and a volunteer group conducted a final search of a landfill where a witness claimed to have seen men dumping a female body.

The behavior specialists from the Netherlands questioned Joran van der Sloot to observe his body language and look for inconsistencies in his account of what happened the night Holloway, 18, disappeared, police spokesman Edwin Comenencia said.

Van der Sloot, 17, has changed his version of events at least once. Originally, he and two Surinamese friends told police they dropped Holloway off at her hotel and then went home May 30, the day she disappeared while on a graduation trip with 124 classmates.

Later, van der Sloot acknowledged to his mother and authorities that he was alone with the Alabama honors student on a beach near the Marriott Hotel, leaving her there but not harming her.

Massive searches near the Marriott, including the recent draining of a pond, have produced no clues. Comenencia said authorities have been searching the area for a pair of white tennis shoes van der Sloot was wearing and apparently lost the day Holloway vanished, but declined to explain their significance to the investigation.