Four men and a woman face federal charges of prostituting a 16-year-old girl and posting her services online on Craigslist.

Marcus Arrington and Anthony Fuller pleaded not guilty yesterday in federal court during their initial appearance to answer several charges of sex trafficking of a minor. The state is transferring the case to federal court where they could get longer prison sentences.

Magistrate Judge Barry Kurren ordered the men held without bail until their trial because of their histories and because they are flight risks. Arrington and Fuller have already been in custody for 10 months.

Brad Yick Kin Young, Spencer Miyahira and Jewel Aquino have also been charged in the alleged sex operation.

Assistant U.S. Attorney Michael Song said the defendants are all in their late teens or early 20s.

Initially, the state charged only Arrington, Fuller and Young with prostitution—punishable by up to 10 years in prison—but federal prosecutors took over the case and added Miyahira and Aquino, who is still at large.

The five defendants are accused of selling sex across state lines by posting an ad online and forcing the girl to work as a prostitute for 10 days in December 2008.

Song said the girl was a runaway and knew her assailants before leaving home.

According to a federal grand jury indictment unsealed last week, Arrington was the pimp who controlled the sex-trafficking operation, collected money paid to the girl and distributed it to the others.

He allegedly used a handgun, ordered her to have sex with customers and instructed her to tell customers she was 18 years old.

He gave the girl, identified only as K.B. in the indictment, cocaine and marijuana to induce her continued compliance, the indictment said.

Police said the girl told officers she went out on calls six to eight times per day to have sex with customers for $200 to $400 and estimated she brought in between $6,000 and $8,000 during the 10 days.

According to the indictment, Fuller, Young and Miyahira provided security and transportation for K.B. when she met with customers.

Miyahira allowed the girl to stay at his residence, and Aquino took a photograph of her and posted an ad for prostitution involving K.B. and herself on Craigslist, the indictment said.

Song said only Aquino is not in custody.

A trial date for the defendants will be set Wednesday.

The defendants face charges of sex trafficking of a minor, which carries a mandatory minimum of 10 years in prison. Arrington faces a mandatory minimum of 15 years in prison if convicted of sex trafficking through force, fraud or coercion.

Song said Fuller and Arrington are also suspects in a robbery case.

The investigation began after the girl escaped and told her mother what happened. Now 17, she has received counseling and is doing well.