Officials said Richard Hill, a Manassas City fire marshal was arrested last week for soliciting a 16-year-old girl to come from Maryland to Virginia for a "sex show".
The FBI said Hill, 45, allegedly took out an ad on Craigslist offering cash to a girl to perform a sex show and for a customer to watch.
The document also said Hill advertised on the MySpace.com Web site, saying that for $300 the customer could enjoy a show you'll never forget.
An FBI agent posing as a customer set up a meeting with Hill, authorities said.
According to court documents, Hill showed up in his city-issued emergency vehicle at a motel in Manassas City on Dec. 14 and a 16-year-old high school student was with him.
The documents stated the FBI agent got a room, called Hill on his cell phone, Hill and the teenager entered the room and after a $250 fee was agreed upon and money was exchanged, officers entered the room and placed Hill under arrest.
He is charged with transportation of a minor for the purpose of prostitution.
Hill's lawyer said Tuesday his client believed the girl was of legal age, which is a defense against the federal charge.
"He believed she was 18. I've never seen her personally, but if you see her, she looks 18," said Lance Gardner. "We believe we will find emails in there where he asks her 'Are you sure you're 18?' She says, 'Yes.'"
A federal judge decided to keep Hill in police custody after a Tuesday detention hearing.
Officials said the sex for money allegations will come under the decision of local authorities because the federal jurisdiction only involves the allegation that Hill played a role in transporting the underage girl across state lines for prostitution.