Peter de Vries said he secretly shot footage of Joran van der Sloot, the main suspect in the May 2005 disappearance of Holloway in Aruba, and another man posing as Dutch sex industry bosses in Thailand and promising work and fake documents to girls willing to join the sex trade, Radio Netherlands reported Monday.
The reporter alleged van der Sloot, who was not prosecuted for Holloway's disappearance due to a lack of evidence, accepted an advance payment of $1,275 for his services from the Thai girls.
Authorities said van der Sloot has not been seen since he was spotted leaving a party Friday night in Bangkok.
Lawyer J.P. Plasman said prosecutors could press charges against van der Sloot for accepting the money.
De Vries said Thai authorities have requested copies of his video footage.